Final Habitat Conservation Plan for Managed Groundwater ... · Aquifer, although also occasionally...

Final Habitat Conservation Plan

for Managed Groundwater Withdrawals from the

Barton Springs Segment of the Edwards Aquifer

Applicant:

Barton Springs/Edwards Aquifer

Conservation District

Prepared by:

Barton Springs/Edwards Aquifer

Conservation District

For:

U.S. Fish & Wildlife Service

Austin, Texas

Last revised – April 18, 2018

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Prepared By:

District Staff:

John T Dupnik, P.G., General Manager

Brian A Smith, Ph.D. P.G., Principal Hydrogeologist

Brian B Hunt, P.G., Senior Hydrogeologist

Justin Camp, Hydrogeologic Technician

Robin H Gary, Senior Public Information Coordinator and GIS Specialist

Kendall Bell-Enders, Regulatory Compliance Coordinator

Vanessa Escobar, Regulatory Compliance Coordinator

Dana C Wilson, Senior Administrative Specialist and Editor

Consultants:

W F (Kirk) Holland, P.G., Management Consultant (and Former GM)

Mary Poteet, Ph.D., University of Texas, Integrative Biology

Art Woods, Ph.D., (Formerly) University of Texas, Integrative Biology

Bryan Brooks, Ph.D., Consultant in Biology and Ecology

Kent S Butler, Ph.D. (Deceased), Project Management Consultant and

Advisor

Under Direction of the District’s 2016-2018 Board of Directors:

Mary Stone, Director Precinct 1

Blayne Stansberry, President, and Director Precinct 2

Blake Dorsett, Secretary, and Director Precinct 3

Robert D Larsen, Ph.D., Director Precinct 4

Craig Smith, Vice President, and Director Precinct 5

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v

Final Habitat Conservation Plan

for Managed Groundwater Withdrawals from the

Barton Springs Segment of the Edwards Aquifer

Table of Contents

Table of Contents ....................................................................................................................................... v

List of Figures ........................................................................................................................................... xi

List of Tables ............................................................................................................................................ xii

List of Acronyms, Abbreviations, and Terms Used in This Document ............................................. xiii

Acknowledgments .................................................................................................................................... xv

Executive Summary .................................................................................................................................. 1

1.0 Introduction and Background ........................................................................................ 5

2.0 Purpose and Need for HCP/ITP ..................................................................................... 7

2.1 Purpose .............................................................................................................................. 7

2.2 Need .................................................................................................................................. 7

2.2.1 Programmatic Basis of Need ............................................................................................. 7

2.2.2 Statutory Basis of Need: Endangered Species Act .......................................................... 10

2.3 Correspondence between HCP Sections and Information Required by Service ............. 10

2.3.1 Information Requirements of an HCP in Support of an ITP ........................................... 11

2.3.2 Findings for Service to Issue an ITP ............................................................................... 11

2.3.3 Additional Guidance and Recommendations for Developing HCPs (“Five Point Policy”)

......................................................................................................................................... 11

3.0 Description of Areas Analyzed ..................................................................................... 13

3.1 Planning Area .................................................................................................................. 13

3.1.1 General Environmental Setting of Planning Area ........................................................... 13

3.1.1.1 Physical Environment ...................................................................................................... 13

3.1.1.2 Biological Environment................................................................................................... 15

3.1.1.3 Man-made Environment .................................................................................................. 17

3.1.2 Hydrogeologic Framework of Planning Area ................................................................. 18

3.1.2.1 Aquifers and Hydrozones ................................................................................................ 19

3.1.2.2 Groundwater Flow Conditions ........................................................................................ 21

3.1.3 Barton Springs/Edwards Aquifer Conservation District Jurisdictional Area .................. 24

3.2 Incidental Take Permit Area ............................................................................................ 25

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3.2.1 Subsurface Part of District’s Exclusive Territory ........................................................... 25

3.2.2 Spring Outlets Area ......................................................................................................... 27

3.2.2.1 Physical Setting ............................................................................................................... 27

3.2.2.1.1 Physical Characteristics of Barton Springs .............................................................. 27

3.2.2.1.2 Sources and Implications of Variation in Springflow at Barton Springs ................. 28

3.2.2.2 Ecological Setting ............................................................................................................ 35

3.2.2.2.1 Overview of Habitat Characteristics and Supported Populations ............................ 35

3.2.2.2.2 Water Chemistry and Springflow Relationships ...................................................... 44

3.2.3 Antecedent Conditions in ITP Area ................................................................................ 49

3.2.4 Protected Species in ITP Area ......................................................................................... 52

4.0 Proposed Actions ........................................................................................................... 53

4.1 Proposed Covered Activities ........................................................................................... 53

4.1.1 Regulated Groundwater Community ............................................................................... 53

4.1.1.1 Exempt Wells and Users ................................................................................................. 57

4.1.1.2 Nonexempt Wells and Users ........................................................................................... 58

4.1.1.2.1 Nonexempt Domestic-Use Wells and Users ............................................................ 59

4.1.1.2.2 Other Nonexempt Wells and Users .......................................................................... 59

4.1.2 Historical Perspective of Covered Activities .................................................................. 62

4.1.2.1 Evolution of Regulatory Program ................................................................................... 62

4.1.2.2 Changes to Pre-HCP Baseline ......................................................................................... 65

4.1.3 Statutory and Regulatory Authorities for Covered Activities and Integrated Conservation

Measures .......................................................................................................................... 68

4.1.4 Public Participation in Developing Covered Activities and Integral Conservation

Measures .......................................................................................................................... 71

4.2 Requested Permit Duration ............................................................................................. 72

5.0 Analysis of Impacts Likely to Result from Taking ..................................................... 75

5.1 Covered Species .............................................................................................................. 75

5.1.1 Species Descriptions and Life Histories .......................................................................... 75

5.1.1.1 Barton Springs Salamander ............................................................................................. 75

5.1.1.2 Austin Blind Salamander ................................................................................................. 79

5.1.2 Species Distribution ........................................................................................................ 79



5.1.3 Reasons for Decline and Threats to Survival .................................................................. 81



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5.1.4 Survival Needs Affected by Covered Activities ............................................................. 93

5.2 Effects of Take on Covered Species ................................................................................ 94

5.2.1 Experimental Assessment of Salamander Responses to Changes in Water Chemistry

Related to Springflow ...................................................................................................... 94

5.2.1.1 Laboratory Study Design ................................................................................................. 95

5.2.1.2 Stressor-Response Study Findings and Applications ...................................................... 96

5.2.1.3 Implications and Limitations of Stressor-Response Study ............................................ 101

5.2.2 Spatial and Temporal Extent of Take ........................................................................... 103

5.2.3 Consideration of Take and Jeopardy ............................................................................ 106

5.2.3.1 Characteristics of Populations Adversely Affected by Take ......................................... 106

5.2.3.2 Apportionment of Springflow-related Take to Adversely Affected Populations .......... 109

5.2.3.3 Consideration of Take Not Related to Springflow ........................................................ 117

5.2.3.4 Cumulative Take Estimates ........................................................................................... 118

5.2.3.5 Considerations for “No Appreciable Reduction” Analysis ........................................... 120

5.3 Impact of Take on Covered Species Populations .......................................................... 129

5.3.1 Assessment of Population Impacts ............................................................................... 129

5.3.2 Uncertainties in Take and Impact Evaluations ............................................................. 133

5.3.3 Comparison with Take Impact Assessment in EARIP ................................................. 137

6.0 Conservation Program ................................................................................................ 141

6.1 Biological Goals and Objectives of HCP ...................................................................... 142

6.2 Minimization and Mitigation Measures ........................................................................ 143

6.2.1 Direct HCP Measures .................................................................................................... 144

6.2.1.1 Providing Most Efficient Use of Groundwater.............................................................. 145

6.2.1.2 Controlling and Preventing Waste of Groundwater ...................................................... 146

6.2.1.3 Addressing Conjunctive Surface Water Management Issues ........................................ 146

6.2.1.4 Addressing Natural Resource Management Issues ....................................................... 147

6.2.1.5 Addressing Drought Conditions .................................................................................... 148

6.2.1.6 Addressing Demand Reduction through Conservation ................................................. 149

6.2.1.7 Addressing Supply through Structural Enhancement .................................................... 149

6.2.1.8 Quantitatively Addressing Established Desired Future Conditions .............................. 150

6.2.2 Other HCP Measures and Strategies, Including Mitigation .......................................... 150

6.2.2.1 Research ........................................................................................................................ 151

6.2.2.2 Mitigation Measures ...................................................................................................... 151

6.2.3 Summary of HCP Measures to Minimize and Mitigate Take ....................................... 154

6.3 Monitoring Activities .................................................................................................... 171

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6.3.1 Monitoring Groundwater Management Actions ........................................................... 171

6.3.2 Monitoring HCP Effectiveness ..................................................................................... 172

6.3.3 Monitoring HCP Implementation .................................................................................. 173

6.4 District HCP Adaptive Management Process ................................................................ 173

6.4.1 Research Supporting the AMP .............................................................................................. 173

6.4.2 AMP Process to Be Used in the District HCP ....................................................................... 174

6.5 Implementation Roles of Plan Participants ................................................................... 176

6.5.1 Barton Springs/Edwards Aquifer Conservation District ............................................... 176

6.5.1.1 Administration and Reporting ....................................................................................... 177

6.5.1.2 District HCP Management Advisory Committee .......................................................... 178

6.5.1.3 Adaptive Management Process ..................................................................................... 179

6.5.1.4 District Enforcement Program ....................................................................................... 179

6.5.2 Cooperating Federal and State Agencies ....................................................................... 181

6.5.2.1 U.S. Fish and Wildlife Service ...................................................................................... 181

6.5.2.2 Texas Parks and Wildlife Department ........................................................................... 181

6.5.3 City of Austin and Barton Springs Pool HCP ............................................................... 181

6.5.4 Other Entities ................................................................................................................. 182

7.0 Changed and Unforeseen Circumstances .................................................................. 185

7.1 Responding to Changed Circumstances and Unforeseen Circumstances ..................... 185

7.1.1 Resolving Adverse Changes .......................................................................................... 185

7.1.2 Method for Developing Criteria for Changed Versus Unforeseen Circumstances........ 186

7.2 Changed Circumstances and Uncertainties ................................................................... 187

7.2.1 Considering the Range of Uncertainties ........................................................................ 187

7.2.1.1 Global Climate Change: Effects and Probabilities ........................................................ 187

7.2.1.2 Effects of Climate Change on Regional Groundwater Systems and Aquifer ................ 189

7.2.1.3 Ecological Significance of Paleoclimatic Indications ................................................... 192

7.2.1.4 Lack of Water Chemistry, Water Quality, and Flow Data to Calibrate Models During

Extreme Low Springflow Conditions ............................................................................ 192

7.2.1.5 Cumulative Negative Effect of Pollutants in Groundwater Discharges on Salamanders

....................................................................................................................................... 193

7.2.1.6 Response of Salamanders to Variations in Habitat Condition ...................................... 193

7.2.1.7 Recent Texas Court Decisions and Aftermath .............................................................. 195

7.2.2 Considering and Responding to Changed Circumstances ............................................. 195

7.2.2.1 Changed Circumstance: Listing of New Species Not Covered by HCP, or Recognition of

Substantial Differences in the Characteristics and Spatial Distribution of Habitats of

Covered Species ............................................................................................................ 196

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7.2.2.2 Changed Circumstance: Unexpectedly Larger Adverse Effects on Springflow

Characteristics and on the Covered Species During Severe Drought In the ITP Term . 197

7.2.2.3 Changed Circumstance: Substantial Change in Statutory, Legal, or Financial Means to

Execute Conservation Measures According to ITP ....................................................... 199

7.2.2.4 Other Changes in Circumstances ................................................................................... 200

7.3 Unforeseen Circumstances ............................................................................................ 201

7.3.1 Determining Occurrence of Unforeseen Circumstances ........................................................ 201

7.3.2 Response to Determination of Unforeseen Circumstances ................................................... 202

7.4 Clarifications, Administrative Changes, and All Other Changes .................................. 203

7.4.1 Clarifications and Administrative Changes ........................................................................... 203

7.4.2 All Other Changes ................................................................................................................. 204

8.0 District HCP Funding Assurances ............................................................................. 207

9.0 Alternatives to Taking................................................................................................. 211

9.1 Analysis of Potential Alternatives to Avoid Take ......................................................... 211

9.1.1 Demand Reduction Alternative ..................................................................................... 211

9.1.2 Supply Enhancement and Substitution Alternative ....................................................... 212

9.2 Basis of Proposed Groundwater Management Program................................................ 213

10.0 Other Information That Secretary May Require ..................................................... 215

11.0 References Cited ......................................................................................................... 217

Appendices (Volume II)

A – Species of Greatest Conservation Need in Planning Area by Ecoregion

B – The BSEACD Sustainable Yield Study (2004)

C – Descriptions of the Habitats and the Flora & Fauna of the Barton Springs Complex

D – Observed Relationships Among Barton Springs Discharge, Water Chemistry, and

Salamander Abundance - 2004

E – User Conservation Plans and User Drought Contingency Plans

F – The District’s Drought Trigger Methodology for the Barton Springs Aquifer

G – Definition of the District’s Groundwater Drought Stages and Related Triggers

H – Entities and Programs for Groundwater Quality Protection in the HCP Planning Area

I – Conservation Physiology of the Plethodontid Salamanders, Eurycea nana and E.

sosorum: Response to Declining Dissolved Oxygen, Woods et al., 2010

J – Supplemental Information on the Springflow, Pumping, and Dissolved Oxygen

Spreadsheet Model

K – The BSEACD Enforcement Plan

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List of Figures

Figure 3-1: Planning Area of District Habitat Conservation Plan. ............................................. 14

Figure 3-2: Locations of Groundwater Flow Paths and Covered Species Habitat in the Barton

Springs segment of the Edwards Aquifer. ................................................................................... 22 Figure 3-3: Barton Springs/Edwards Aquifer Conservation District Jurisdictional Area. ......... 26 The District has different regulatory authorities in the Shared Territory and the Exclusive

Territory. ...................................................................................................................................... 26

Figure 3-4: Incidental Take Permit Area of the COA’s Barton Springs Pool Habitat

Conservation Plan. ....................................................................................................................... 28 Figure 3-5: Reconstructed combined daily flows at Barton Springs under a condition of no

pumpage, 1917–2013. .................................................................................................................. 29

Figure 3-6: Variable flow at Barton Springs, September 2006–October 2014........................... 31 Figure 3-7: Various regression models representing relationships between springflow of the

aggregated sub-outlets of Main Springs and dissolved oxygen concentration. ........................... 47 Figure 3-8: Example of inverse relationship between springflow and water salinity at Main

Springs, expressed as specific conductance. ................................................................................ 50 Figure 3-9: Pumpage history showing District milestones. ........................................................ 51 Figure 4-1: Location of Aquifer wells in ITP Area and use type. .............................................. 56 Figure 4-2: Computed Barton Springs flow, 1917–2013, under three conditions: exempt-only

pumping, pre-Habitat Conservation Plan pumping, and Habitat Conservation Plan pumping. .. 67 Figure 5-1: (Above) Barton Springs salamander, Eurycea sosorum; (below) Austin blind

salamander, E. waterlooensis. ...................................................................................................... 76 Figure 5-3: Example setups for studying salamander response to stressors . ............................. 96

Figure 5-4: Relationship between mortality of San Marcos salamander and five exposure

concentrations of dissolved oxygen in a laboratory study. .......................................................... 97

Figure 5-5: Recurrence (nonexceedance) frequency of Barton Springs flow for the period of

record under three groundwater management scenarios. ........................................................... 111

Figure 5-6a: Nonexceedance frequency for dissolved oxygen concentration for the period of

record at Main Springs under three groundwater management scenarios. ................................ 112 Figure 5-6b: Nonexceedance frequency for dissolved oxygen concentration for the period of

record at Eliza Spring under three groundwater management scenarios. .................................. 112

Figure 5-6c: Nonexceedance frequency for dissolved oxygen concentration for the period of

record at Old Mill Spring under three groundwater management scenarios. ............................ 113 Figure 5-7: Modeled Barton Springs flow during DOR conditions under three groundwater

management scenarios. .............................................................................................................. 114 Figure 5-8: Diagram showing reference period and logic used for computing the monthly take

factor. ......................................................................................................................................... 116 Figure 5-10a: Dissolved oxygen concentrations at Main Springs during DOR conditions under

three groundwater management scenarios and proposed mitigation measures. ........................ 125 Figure 5-10b: Dissolved oxygen concentrations at Eliza Spring during DOR conditions under

three groundwater management scenarios and proposed mitigation measures. ........................ 126 Figure 5-10c: Dissolved oxygen concentrations at Old Mill Spring during DOR conditions

under three groundwater management scenarios and proposed mitigation measures. .............. 127 Figure 5-11: A proposed adverse outcome pathway (AOP) in the Covered Species for dissolved

oxygen. ....................................................................................................................................... 131 Figure 7-1: Change in annual precipitation projected over Texas by mid-century. ................. 189

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List of Tables

Table 3-1: Recurrence (nonexceedance) frequencies of natural (no Aquifer pumpage)

springflow for specified drought management thresholds. .......................................................... 30

Table 3-2: Population statistics of the Covered Species based on surface survey counts. ......... 37 Table 3-3: Estimated population distribution of Austin blind salamander at each outlet. .......... 41 Table 3-4: Federally protected species in Travis, Hays, and Caldwell Counties, Texas. ........... 52 Table 4-1: Public water system permittees using the Aquifer. ................................................... 54 Table 4-2: Estimated/authorized groundwater withdrawal in the ITP Area by withdrawal type.

...................................................................................................................................................... 55 Table 4-3: Mandatory curtailment of water withdrawals. .......................................................... 61

Figure 4-3: Barton Springs/Edwards Aquifer Conservation District 2016 director precinct

boundaries. ................................................................................................................................... 69 Table 4-4: Legislation affecting District authority. .................................................................... 70 Figure 5-2: Service-designated Critical Habitat for the Austin blind salamander. ..................... 82

Table 5-1: Summary of threats to Covered Species.................................................................... 85 Table 5-2: Summary Lethal Concentrations and Dissolved Oxygen Concentration (Woods et

al., 2010). ..................................................................................................................................... 98

Table 5-3: Summary of growth rates of juvenile San Marcos salamander over 60 days in

different dissolved oxygen concentrations. .................................................................................. 99

Table 5-4: Likelihood (percent chance) that DO concentrations in springflow at Main Springs,

Eliza Spring, and Old Mill Spring would be at or below response thresholds for San Marcos

salamander. ................................................................................................................................ 100

Table 5-5: Toxicological benchmark concentrations for low percentiles, Main Springs, Eliza

Spring, and Old Mill Spring....................................................................................................... 101 Table 5-6: Onset of take by spring outlet.................................................................................. 105 Table 5-7: Total stipulated population of the Barton Springs salamander by location. ........... 107

Table 5-8 provides a summary of the total populations and locations of the Austin blind

salamander that may encounter adverse effects from the Covered Activities. .......................... 108

Table 5-8: Total stipulated population of Austin blind salamander by location. ...................... 108 Table 5-9: Derivation of monthly take factors for Covered Species during droughts. ............. 115 Table 5-10: Summary of cumulative take of Barton Springs salamander for 20-year ITP term.

.................................................................................................................................................... 119

Table 5-11: Summary of cumulative take of Austin blind salamander for 20-year ITP term. . 119 Table 6-1: Summary of HCP Measures and correspondence with Management Plan objectives

and performance standards ........................................................................................................ 155 Table 6-2a: Daily penalties for violations of District drought rules during Stage II-Alarm

Drought, Rule 3-7.7.B(1). .......................................................................................................... 180 Table 6-2b: Daily penalties for violations of District drought rules during Stage III-Critical and

Stage IV-Exceptional Drought, Rule 3-7.7.B(2). ...................................................................... 180

Table 6-2c: Definition of tiers of permitted pumpage and levels of overpumpage during all

drought stages. ........................................................................................................................... 181

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List of Acronyms, Abbreviations, and Terms Used in This Document

Act, the The federal Endangered Species Act

AF Acre-feet (equivalent to 1.233 million liters)

AMP Adaptive Management Plan

BAT Biological Advisory Team

BSEACD Barton Springs/Edwards Aquifer Conservation District

C Celsius, temperature scale

CAC Citizens Advisory Committee

CCSP U.S. Climate Change Science Program

CFR Code of Federal Regulations

cfs cubic feet per second (equivalent to 0.0283 cubic meters per second)

CO2 carbon dioxide

COA City of Austin

COMM Commercial, water use type

DFC Desired Future Condition

DISTRICT Barton Springs/Edwards Aquifer Conservation District

DO Dissolved Oxygen

DOI U.S. Department of the Interior

DOR Drought of Record

EAA Edwards Aquifer Authority

EIS Environmental Impact Statement

ERP Emergency Response Period (drought stage)

ESA Endangered Species Act (the Act)

FR Federal Register

GBRA Guadalupe-Blanco River Authority

GCD Groundwater Conservation District

GCM Global Circulation Model

GMA Groundwater Management Area

GWSIM- IV USGS groundwater flow model

HCP Habitat Conservation Plan

ILA Interlocal Agreement

IND Industrial, water use type

IPCC Intergovernmental Panel on Climate Change

IRG Irrigation, water use type

ITP Incidental Take Permit

LCx Lethal Concentration [x is percentage of total]

MAC Management Advisory Committee;

MAG Modeled Available Groundwater (derived from DFC)

MG million gallons (equivalent to 3.785 million liters)

mg/L milligrams per liter (chemical concentration; numerically equal to

parts per million)

mm millimeter (equivalent to 0.0394 inch)

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MP [District] Management Plan

msl mean sea level, datum for elevation measurement

NDU Nonexempt Domestic Use

NEPA National Environmental Policy Act

NOAEL No Observed Adverse Effect Level

PEHA Probabilistic Ecological Hazard Assessment

pH Concentration of hydronium ion (acid-base measure) Production

PWS

(Amount of) groundwater withdrawn by pumping water well(s)

Public Water Supply, water use type

Pumpage Amount of groundwater pumped from water well(s)

r Correlation Coefficient

R2 Coefficient of Determination

SAP Synthesis and Assessment Product

SD Standard Deviation

Service U.S. Fish and Wildlife Service, Department of the Interior

SYS Sustainable Yield Study

TCEQ Texas Commission on Environmental Quality

TDS Total Dissolved Solids (a measure of salinity)

TPWD Texas Parks & Wildlife Department

TWC Texas Water Code

TWDB Texas Water Development Board

UCP User Conservation Plan

UDCP User Drought Contingency Plan

U.S.C. United States (Government) Code

USEPA United States Environmental Protection Agency

USGS United States Geological Survey

Withdrawal(s) Groundwater withdrawn from aquifer by pumping water well(s)

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Acknowledgments

The Barton Springs/Edwards Aquifer Conservation District (BSEACD) prepared and is

submitting the Habitat Conservation Plan (HCP) as the sole Plan Participant, and the

BSEACD alone is responsible for the contents of the HCP. However, the BSEACD was

assisted in the preparation of various drafts of the HCP and in the conduct of supporting

investigations by a set of contractors that provided important contributions to the overall

effort. The contractors are:

• Hicks & Company, for environmental impact assessment and NEPA-related

documentation;

• Recon Environmental, Inc., for HCP documentation and planning consulting services;

• Bio-West, for ecological impact assessments;

• LBG-Guyton Associates, for hydrogeological consultation;

• Dr. Bryan Brooks, Baylor University, probabilistic ecological hazard assessments;

• Dr. Mary Poteet, University of Texas at Austin, laboratory studies of stressor-

responses in salamanders;

• Dr. Art Woods, (then) University of Texas at Austin, laboratory studies of stressor-

responses in salamanders;

• Raymond Slade, Certified Professional Hydrologist, for analysis of Barton Springs

flow records;

• Dave Anderson, FORM Strategic Consulting, LLC, for establishing and coordinating

initial activities of the HCP Management Advisory Committee;

• Dr. Kent Butler, Butler & Associates, project management and coordination

consultation;

• W F (Kirk) Holland, Holland Groundwater Management Consultants LLC, for overall

project management, documentation, and coordination; and

• Peter Bush, Technical Editor.

In addition, various members of the Watershed Protection Department and Austin Water

Utility of the City of Austin and the Austin Ecological Field Office of the U.S. Fish and

Wildlife Service provided invaluable continuing assistance during the development and

documentation of the HCP.

Moreover, the District has assembled a multilateral stakeholder group to serve as a

continuing HCP Management Advisory Committee (MAC) to advise the District Board of

Directors and assist the District staff in implementing the HCP, as described in Section

6.5.1.2, District HCP Management Advisory Committee. The inaugural members of the

MAC also participated in a comprehensive, facilitated review process of earlier versions of

the HCP, and their comments substantially improved the final draft document. These

members and their affiliations/interest groups are:

Brian Smith BSEACD Aquifer Science Team (District Technical Staff)

Cindy Loeffler Texas Parks & Wildlife Department (TPWD)

Chris Herrington City of Austin Watershed Protection (COA WPD)

Jennifer Walker Sierra Club (Environmental Community)

xvi

Bryan Brooks Baylor University (Technical/Ecological Research Expert)

Laurie Dries City of Austin WPD (City Salamander Biologist/Expert)

Jason Biemer City of Kyle (Public Water Supply Permittee)

David Loftis Centex Materials (Large Private Sector Permittee)

Scott Nester Property Owner in District (Aquifer-using Landowner)

Christy Muse Hill Country Alliance (Private Property/Conservation)

Todd Votteler Guadalupe Blanco River Authority (River Authority)

Jon White Travis County (County Government)

Clif Ladd Interested Private Citizen (Public At-Large)

Karen Huber Interested Private Citizen (Public At-Large)

The HCP was developed, refined, and reviewed through a rigorous public process and

benefitted from input and recommendations from current and past Board members,

stakeholders, subject experts, and advisory committee members. The contributing BSEACD

Board members are:

Mary Stone Precinct 1 Director

Chuck Murphy Former Precinct 1 Director

Blayne Stansberry Precinct 2 Director

Gary Franklin Former Precinct 2 Director

Blake Dorsett Precinct 3 Director

Robert D Larsen, Ph.D. Precinct 4/Former Precinct 3 Director

Jack Goodman Former Precinct 4 Director

Craig Smith Precinct 5 Director

The District sincerely appreciates the past and future contributions of the many individuals

who selflessly give their time and perspectives to benefit this HCP and the public interest.

1

Executive Summary

The Barton Springs/Edwards Aquifer Conservation District (District) is a Texas groundwater

conservation district charged with the management of the Barton Springs segment of the

Edwards Aquifer (Aquifer), which is the primary water supply for more than 60,000 people in

the region and the source water for the Barton Springs complex. The District manages this

resource by a production permit-based regulatory program for larger, non-exempt wells, and this

program’s elements constitute the Covered Activities. The overarching strategic purpose of the

District is to optimize the sustainable uses of groundwater for these users and other community

interests. However, it is well established that during drought conditions large amounts of

groundwater withdrawals (pumping) will contribute to diminished flow through the Aquifer and

smaller springflow rates at Barton Springs and associated adverse effects to some Aquifer users.

The Aquifer and its associated spring outlets are the sole habitat of the federally-protected Barton

Springs salamander (BSS) and Austin blind salamander (ABS). The federal Endangered Species

Act prohibits the harassment or harm of the salamanders (termed “take”) that may incidentally

occur as a result of the effect of pumping on decreasing water levels and springflows unless

exempted under a federal Incidental Take Permit (ITP). Without an ITP, District permittees

could be held responsible for take and in violation of the federal law.

This document presents the District’s Habitat Conservation Plan (HCP) supporting an

application of an ITP for a 20-year period. The permit would allow for continued managed

pumping (the covered activity) of the Aquifer by District permittees, provided the proposed HCP

measures minimize and mitigate the incidental take and avoids jeopardy (the inability of the

salamander to survive or recover from the take) of salamanders. Ultimately, the HCP measures

safeguard the continued sustainable use of the Aquifer and survival of the endangered

salamanders.

To develop an HCP the District conducted numerous studies and began implementing

preemptive conservation measures in 2004. The HCP integrates numerous hydrogeologic and

biological studies to develop a conceptual model of the relationship between pumping,

springflow, dissolved oxygen (DO), and the potential effects on salamanders. During drought,

pumping of groundwater from the Aquifer decreases the already diminished springflows that

naturally discharge from the Aquifer on a nearly one-to-one volumetric basis. There is an

established correlation between springflows and DO. Generally, lower springflows contain

lower DO concentrations (less oxygen in the water). Biological studies document the effects of

varying levels of DO on the salamanders. Thus, pumping during drought conditions decreases

water levels and springflow, which in turn is associated with reduced DO levels that ultimately

may have adverse effects on the salamanders, which creates incidents of “take.” These

relationships were incorporated into a spreadsheet-based numerical model and used to evaluate

the impacts of various HCP measures on water in the Aquifer as reflected in springflow and its

DO. While the conceptual and simple numerical models represent the best available science, the

assumptions and relationships in both models are believed to be generally conservative and

likely over-estimate the adverse effects of pumping on springflow and its DO, and therefore the

adverse impacts on the habitat.

To protect the salamanders and preserve water supplies the District has adopted policies in its

2017 Management Plan and additional measures described in the HCP to reduce average annual

2

pumping from the Aquifer to no more than 5.2 cubic feet per second (cfs), or 0.15 cubic meters

per second (m3/s), to preserve a minimum of 6.5 cfs (0.18 m3/s) of springflow during a

recurrence of drought of record (DOR) conditions. To avoid and minimize take, the HCP

commits to specific measures and actions that include: establishing a permitting cap on firm-

yield pumping; employing a drought management program to define drought severity and

requisite pumping curtailments (up to 50%); and encouraging the substitution of Aquifer supplies

with alternative water supplies (e.g., Trinity, aquifer storage and recovery (ASR), desalination)

among other measures. The HCP further commits to continue research initiatives including

refinement of the conceptual hydrogeological and ecological models and to implement specific

mitigation measures including: support of an existing salamander refugium, continued recharge

enhancement and pollution prevention measures at Antioch Cave, an abandoned well program, a

DO augmentation program (if feasible), and other specified aquifer protection measures.

The conceptual and numerical models developed for this HCP allow comparison of the estimated

monthly springflow and corresponding DO values for three scenarios, including: exempt-only

pumping, pumping without HCP measures, and pumping with HCP measures. Results indicate

that the HCP will allow the District to manage drought springflows and minimize adverse

impacts to the salamanders by reducing the frequency of low flows, and raising the minimum

DO values. For example, for a 97-year period of record we estimate springflows could reach 10

cfs (0.283 m3/s) (Emergency Response Period) 3% of the time with HCP pumping measures in

place, and more than double at 7% without HCP pumping measures in place.

The HCP measures (including all mitigation measures) reduce both the amount of take and the

likelihood of jeopardy of the endangered salamanders during a recurrence of DOR conditions.

During the DOR and with then-allowable pumping and the proposed HCP measures, average DO

at the perennial spring outlets is estimated to be about 4.2 milligrams per liter (mg/L) without

mitigation, and minimum DO concentrations would be below 3 mg/L only for three months and

would never fall below 2 mg/L. But with the proposed mitigation the average DO would be even

higher, about 4.7 mg/l, similar to natural conditions with exempt-only pumping and no

mitigation measures. These outcomes are much more positive than what would be expected with

no HCP measures, where the DO would average about 3.7 mg/L and would be less than 3 mg/L

for about 17 months, including zero for two months. Investigations commissioned for this HCP

indicate that salamander populations are not adversely affected physiologically by DO

concentrations of 4.5 mg/L or greater, and are only mildly affected by DO concentrations slightly

lower, at 4.2 mg/L. Thus, while the HCP measures are not able to avoid take, they do minimize

the amount of take that occurs and the frequency with which it occurs.

Using the conceptual model and best professional judgment the District estimated the amount of

take that would occur during the course of a severe drought. Drought effects begin to physically

modify the amount of habitat at the non-perennial Upper Barton Spring, beginning at 40 cfs

(1.13 m3/s) or less of combined springflow (the “habitat modification take” threshold). If

drought continues to deepen, when combined springflows decline to 30 cfs (0.85 m3/s) or less on

a monthly basis (corresponding to 5.0 mg/L DO or less), the conservatively stipulated threshold

initiating “behavioral take” at the perennial outlets is reached. Then if the combined springflows

continue to decline to 20 cfs (0.565 m3/s) or less on a monthly basis (corresponding to 4.5 mg/L

DO or less), the stipulated threshold initiating “physiological take” at the perennial outlets is

reached, and such take is in addition to the behavioral take. During such severe drought

3

conditions, a conservatively estimated 174 and 36.6 incidents of take per drought month occur on

average for the BSS and ABS, respectively. Conservatively using 14 years of severe drought

conditions (including 7 years of a possible but unlikely DOR recurrence) over the next 20 years

(length of the permit), the District estimates up to 20,200 and 4,260 incidents of “take” could

occur for the BSS and ABS, respectively during that time.

The HCP was developed, refined, and reviewed through a rigorous public process and benefitted

from input and recommendations from stakeholders, subject experts, and advisory committee

members. With the proposed HCP conservation measures in place and with the proposed

monitoring, adaptive management, and reporting programs described in this HCP the District

reasonably expects to be able to achieve the objectives of sustainably managing use of the

Aquifer as a water supply, minimizing and mitigating the incidental take of the salamanders,

ensuring their survival, and the avoidance of jeopardy.

4


5

Final Habitat Conservation Plan for

Managed Groundwater Withdrawals

from the Barton Springs Segment of the

Edwards Aquifer

1.0 Introduction and Background

This habitat conservation plan (HCP) is proposed by the Barton Springs/Edwards Aquifer

Conservation District (BSEACD, or the District) in support of an application for an incidental

take permit (ITP, or Permit) from the U.S. Fish and Wildlife Service (Service) for the Barton

Springs salamander (Eurycea sosorum; BSS) and for the Austin blind salamander (E.

waterlooensis; ABS), both protected species listed as endangered by the Service (together, the

Covered Species). The term "take" refers to an action and its associated adverse effects on

members of any threatened or endangered species. The District is a political subdivision of

the State of Texas, a local agency of the State that was formed and authorized by the Texas

Legislature specifically to manage the groundwater resources within its jurisdiction under

applicable state laws and statutes, particularly Texas Water Code Chapter 36 and Special

District Local Laws Code Chapter 8802. This document constitutes the HCP for the regulated

withdrawal of groundwater of the Barton Springs segment of the Edwards Aquifer as a water

supply by permitted well owners/operators under the conservation program and auspices of

the District (hereinafter, District HCP). It proposes a substantial number of regulatory and

groundwater management measures that will be implemented by the District as HCP

conservation measures upon issuance of an ITP under Section 10 of the Endangered Species

Act, as Amended (16 U.S.C. 1531-1539)(Act)).

Issuance of an ITP is a federal action subject to a review by the Service in compliance with

the National Environmental Policy Act (NEPA), which may involve preparation and further

documentation of overall environmental consequences in an Environmental Assessment or

Environmental Impact Statement (EIS). The District HCP focuses exclusively on the

biological and ecological effects and consequences of certain District actions as they relate

specifically to the Covered Species. A separate NEPA document presents the Service’s

analysis of the direct, indirect, and cumulative impacts of issuing the requested ITP on all of

the natural and the man-made environments.

The District HCP is a public document under the Texas Public Information Act. It is the

District’s intent that this document provides such additional context and information, beyond

that required by the Service, to be comprehensible and useful to the District’s stakeholders,

including District permittees and the state, regional, and local entities affecting and affected

by the HCP. However, an HCP is essentially a proposal to the Service that informs a Service-

internal consultation process specifically designed to form a Biological Opinion on the likely

6

effects and consequential impacts on the Covered Species, which then becomes the basis for

decision-making on issuance of an ITP. As such, its format, content, and level of detail are

largely prescribed by Service regulations, policy, and guidance.

The District’s statutory mandate is to provide for the conservation, preservation, and

protection of groundwater resources of all aquifers in its jurisdictional area, including parts of

northwestern Caldwell, northeastern Hays, and southeastern Travis Counties. This area

encompasses all sites of groundwater withdrawal from the Barton Springs segment of the

Edwards Aquifer, sometimes called the Barton Springs aquifer (hereinafter, the Aquifer,

unless narrative context requires additional specificity). This mandate is consistent with the

HCP; and the same measures that benefit the Aquifer’s human users, by extending the water

supply during drought, also benefit the Covered Species that depend on the Aquifer as habitat.

The District’s activities described by this HCP are consistent with current (2014) statutory

authorities of the District and are based on sound science and effective groundwater

management practices. They have been formulated and framed in collaboration with other

conservation efforts affecting the Covered Species and/or their habitat. In particular this

includes the City of Austin’s (COA) July 2013 “Major Amendment and Extension of the

Habitat Conservation Plan for the Barton Springs Salamander (Eurycea sosorum) and the

Austin Blind Salamander (Eurycea waterlooensis) to Allow for the Operation and

Maintenance of Barton Springs and Adjacent Springs” (hereinafter, the Barton Springs Pool

HCP). Certain aspects of the Edwards Aquifer Recovery Implementation Plan/HCP for the

use and management of the adjacent San Antonio segment of the Edwards Aquifer (EARIP,

2012) were relevant to and useful in developing the District’s HCP.

The biological goals and objectives of the District’s conservation program are listed in Section

6.1, Biological Goals and Objectives of the HCP. Other District goals and objectives are

characterized in the current Texas Water Development Board (TWDB)-approved District

Management Plan (BSEACD, 2017) and have been designed to be consistent with the goals and

objectives described in this HCP.

7

2.0 Purpose and Need for HCP/ITP

2.1 Purpose

As described above, the District’s statutory mandate is to provide for the conservation,

preservation, and protection of groundwater resources of all aquifers in its jurisdictional area.

Certain activities associated with that mission may produce both beneficial and adverse effects

on the rate and water chemistry of springflow at Barton Springs that in turn impact the habitats

of the Covered Species. In particular, the District’s drought management program both allows

and restricts the amount of groundwater withdrawn from the Aquifer by certain well owners.

Nevertheless, the federal Endangered Species Act (Act) prohibits take of its listed species except

as prescribed in the Act. The purpose of the District HCP is to meet the requirements of

applying for and receiving an ITP under the Act (see Section 2.2.2, Statutory Basis of Need:

Endangered Species Act). The purpose of the ITP is to allow the District, on a federally

authorized exception basis, to continue to carry out its State-authorized, otherwise lawful

activities that may result in incidental take of the Covered Species.1

2.2 Need

2.2.1 Programmatic Basis of Need

The District’s activities that create the need for an HCP and an ITP relate to the following

groundwater management functions that are explained in the District Management Plan (District,

2017):

• Adopt, implement, and enforce regulations and management programs that protect existing

groundwater supplies, improve aquifer demand management, provide Aquifer and springflow

protection during droughts, promote and improve aquifer recharge, and carry out other

beneficial management strategies; and

• Avoid, or minimize, and mitigate negative impacts upon federally listed species dependent

upon springflow from Barton Springs through adoption and implementation of regulations,

management programs, scientific research programs, conservation education programs, and

collaborative efforts with other governmental entities.

These activities directly and indirectly affect withdrawals (pumpage) from the Aquifer (the

amount of groundwater withdrawn by operating pumps set in wells [pumping wells] installed

within the Aquifer for providing the water supply of well owners/operators). In turn, as a result

1 The Covered Species may also be stressed by the introduction of pollutants that affect the quality of water recharging

the Aquifer. Unlike the natural water chemistry changes, these water quality impacts are generally caused by human

activities on the land surface that result in pollution from point sources and especially nonpoint sources. In this

document, these impacts are referred to as “water quality” impacts, to distinguish them from “water chemistry” impacts.

The water quality impacts of these actions, over which the District has no control and therefore are not Covered

Activities, are cumulative with the natural changes in water chemistry associated with lower springflows, and both are

generally antagonistic to aquatic life requirements.

8

of the hydrology of the groundwater system, such withdrawals lower the elevation (altitude

referenced to mean sea level) of water levels in the Aquifer, which consequently reduces the

discharge (springflow, or flow) at Barton Springs. There is a well-established relationship,

within the observed data range, between the flow issuing from the outlets of Barton Springs and

the chemistry of the water. As flow decreases, the dissolved oxygen (DO) concentration of the

water, which is required by the Covered Species for survival, decreases, and the concentration of

dissolved solids increases. This natural variation in water chemistry derives from the physical

system of the Aquifer, and it occurs regardless of whether Aquifer water-levels and springflow

decreases are due to drought, withdrawals by wells, or both (BSEACD, 2013; BSEACD, 2004).

During normal and high-flow conditions in the Aquifer, the combined flow of the natural outlets

at Barton Springs are many multiples of the total amount of water that is being withdrawn by

wells in the Aquifer. Under these conditions, the District’s program elements principally address

the long-term sustainability of the Aquifer as a water supply. Under these conditions, the

amount of water withdrawn from the Aquifer by wells and the provisions of the District’s

regulatory program are believed to have essentially no effect on the chemistry of the springflow.

This is because the physical and chemical characteristics of the springflow are mostly

attributable to meteorologically induced stormflows and seasonal factors, and from time to time,

other external factors (Mahler and Bourgeais, 2013; Mahler et al., 2011). Accordingly,

essentially no incidental take is attributable to the Covered Activities (lawfully conducted

withdrawals from District permitted wells, see Section 4.1, Proposed Covered Activities) when

water levels in the Aquifer are above a certain elevation, which determines the flow at the

Aquifer’s major outlet, Barton Springs. This threshold elevation and flow are characterized in

Section 3.2.2.1, Physical Setting.

But during drought, and especially prolonged severe or Extreme Drought2, the amount of water

naturally discharging from the springs complex (the natural spring outlets taken together) is

much smaller, similar in magnitude to the amount of water withdrawn from wells. During these

drought conditions, the District’s groundwater drought management program is key to preserving

groundwater levels in the Aquifer and springflow. The joint and regional water planning

conducted by the State, with which the District’s groundwater management plan is integrated,

uses a recurrence of the drought of record in the 1950s (DOR) as the planning objective, and the

DOR is also the framework for the District’s drought management program. The District’s

integrated regulatory program is designed to protect the water supply of Aquifer users who are

most vulnerable to supply interruption during periods of Extreme Drought and to conserve the

flows at Barton Springs for both ecological and recreational purposes.

2 “Severe drought” is a general term used herein to refer qualitatively to conditions that represent those groundwater

drought conditions in the District that range from prolonged Stage II-Alarm through Stage IV-Exceptional Droughts, as

defined and declared by the District. See Section 4.1.1.2.2 and Appendices E, F, and G for more information on

drought stage definition and drought management implementation. “Extreme Drought” is defined by current (2016)

District Rules as: “…a severe drought period, deep within a Stage IV Exceptional Drought, that is characterized by the

sustained flow at Barton Springs at or below 10 cubic feet per second (cfs) (0.28 m3/s) on a 10-day running average

basis…”.

9

It is during certain of these drought periods that the groundwater levels and springflows

unavoidably decline sufficiently to create incidental take of the Covered Species, which creates

the programmatic need for the HCP and the ITP. The circumstances that give rise to such

incidental take are discussed in detail in Section 5.2.2, Spatial and Temporal Extent of Take, and

Section 5.2.3, Consideration of Take and Jeopardy.

Demand for and withdrawal of groundwater for public water supply and other beneficial uses have

increased substantially in recent decades, which in turn increase the need for programmatic action.

For many users, the Aquifer continues to be the only feasible water supply available. The

cumulative withdrawals of all operating wells in the Aquifer can have significant impact on

springflow during drought conditions and can increase the likelihood of low-flow conditions.

During severe drought, the impact of withdrawals may produce habitat-significant water chemistry

changes, as will be characterized in Section 3.2.2.2, Ecological Setting. The withdrawal from

permitted operating wells reached an all-time monthly peak of approximately 13.4 cubic feet per

second (cfs) (equivalent to 3.21 billion gallons, or 12.1 billion liters, per year) in June 2008

(BSEACD, unpublished data, 2014).

Since June 2008, despite increased demand for water supplies in the District, withdrawals generally

have been reduced as a result of groundwater management policies and regulations of the District

and of responses by its permittees to projected shortfalls during severe droughts. As the demand for

groundwater has increased, the District has gradually changed its drought management and

regulatory program to improve the effectiveness of Aquifer and springflow protection, supported in

no small part by the studies and planning for the ongoing HCP development. Monthly average

pumpage for the 3 years 2007–09 was 8.2 cfs (0.23 m3/s), which also included a regulated drought

period in 2008–09 with mandatory pumpage reductions of 20 and 30% during District-declared

Stage II-Alarm and Stage III-Critical drought, respectively (BSEACD, 2010). Withdrawals were

once predicted to increase steadily with urban development over the Aquifer and reach as much as

19.6 cfs (0.55 m3/s) by 2050 (Scanlon et al., 2001). However, owing to the implementation of

conservation plans, demand-management programs, and imposition of severe drought-withdrawal

limitations by the District (described in Section 6.2, Minimization and Mitigation Measures), the

estimated maximum withdrawals over the long term are now considerably lower, no more than

about one-quarter of that previously projected peak of 19.6 cfs

The HCP specifies the District commitments to a set of conservation (avoidance, minimization,

and mitigation) measures that are consistent with statutory authorities of the District and that are

based on sound science and effective groundwater management practices. The District HCP has

been formulated and framed in collaboration with other conservation efforts affecting the

Covered Species and their respective habitats; that is, the habitat conservation plan of the COA

for operation and maintenance at Barton Springs Pool and surrounding area, including

particularly the individual spring outlets (Barton Springs Pool HCP). The well owners and users,

especially the District’s permittees as described in Section 4.1.1 (The Regulated Groundwater

Community), and all citizens who consider Barton Springs an ecological, recreational, and

aesthetic resource, are the key additional stakeholders for this HCP.

10

2.2.2 Statutory Basis of Need: Endangered Species Act

Regulations for implementing the Act and for issuing permits are found in Title 50, Sections 15

and 17 of the Code of Federal Regulations (50 CFR §15 and §17), which are the relevant federal

statutes that protect and promote the recovery of endangered and threatened species. Section 9

of the Act (16 U.S. Code [U.S.C.] 1538(a)) prohibits “take” of any federally endangered wildlife.

As defined by the Act, “take means to harass, harm, pursue, hunt, shoot, wound, kill, trap,

capture, or collect, or to attempt to engage in any such conduct” relative to any threatened or

endangered species. Section 10(a)(1)(B) of the Act of 1973 (16 U.S.C. 1539(a)(1)(B))

authorizes the U.S. Fish & Wildlife Service (Service) to issue a permit (or ITP) allowing on a

conditional and exception basis the take of protected species that is incidental to, and not the

purpose of, the carrying out of otherwise lawfully conducted activities (Covered Activities). For

the issuance of an ITP, the applicant must submit a conservation plan that satisfies the

requirements of Section 10(a)(2)(A) of the Act. The required elements of an HCP and ITP under

the Act are identified in Section 2.3, Correspondence between HCP Sections and Information

Required by Service.

Section 10(a)(2)(B)(ii) of the Act allows non-federal entities to conduct otherwise lawful

activities likely to cause take of endangered species, as long as the detrimental effects of the

activities are not purposeful and are minimized and mitigated to the maximum extent practicable;

and further provides that the Service determines that jeopardy of the Covered Species’

populations related to the Covered Activities is avoided. "Jeopardy" occurs when an action is

reasonably expected, directly or indirectly, to diminish a species’ numbers, reproduction, or

distribution so that the likelihood of survival and recovery in the field is appreciably reduced.

HCPs are the vehicles by which such take can be authorized by the Service on an exception

basis, provided that it will be minimized and mitigated by the ITP applicant to the maximum

extent practicable. This HCP is expressly designed to fulfill those obligations of the District for

the regulated groundwater withdrawal from the Aquifer (its Covered Activities).

2.3 Correspondence between HCP Sections and Information

Required by Service

The location of the information required or pertinent for an HCP to comply with Service

regulations and guidance is tabulated in the following subsections. These correspondence tables

are provided to assist not only the Service but also and especially the District’s stakeholders and

the public in finding and reviewing information that relates the descriptions of the District’s

groundwater management programs to the required conservation plan elements.

11

2.3.1 Information Requirements of an HCP in Support of an ITP

Service Requirement (16 U.S.C. § 1539(a)(2)(A)(i)-(iv) HCP Section(s)

1. The impact that will likely result from the taking; 5.2; 5.3

2a. Steps the applicant will take to monitor, minimize, and

mitigate such impacts,

6.0; 6.1; 6.2; 6.3;

6.4; 6.5.1; 7.1; 7.2.2

2b. The funding available to implement the steps, and 8.0

2c. The procedures to be used to deal with unforeseen

circumstances; 7.3

3. Alternative actions to the proposed taking considered by

the applicant and the reasons why such alternatives are

not proposed to be used; and

9.0; 9.1; 9.2

4. Other measures that may be required or appropriate for the

purposes of the plan.

None yet identified,

but see 6.4; 6.5.1.3;

7.1

2.3.2 Findings for Service to Issue an ITP

Service Requirement (16 U.S.C. § 10(a)(2)(B) HCP Section(s)

1. The taking will be incidental; 1.0; 2.1; 4.1

2. The applicant will, to the maximum extent practicable,

minimize and mitigate the impacts of such taking; 6.0-6.4; 7.0-73; 9.2

3a. The applicant will ensure that adequate funding of the

conservation plan [will be provided], and 8.0

3b. [The applicant will ensure that] procedures to deal with

unforeseen circumstances will be provided; 7.2, 7.3

4. The taking will not appreciably reduce the likelihood of

survival and recovery of the species in the wild; and

5.1.3;.5.1.4; 5.2.3.4;

5.3

5. The applicant will ensure that other measures as may be

required by Service as necessary or appropriate for

purposes of the HCP will be implemented.

1.0; 4.1.2.1; 4.1.3;

6.1; 6.3; 6.4; 6.5.1;

7.0-7.3; 8.0

2.3.3 Additional Guidance and Recommendations for Developing

HCPs (“Five Point Policy”)

HCP Handbook Addendum (65 FR3 32,250-32,256) HCP Section(s)

1. Defined conservation goals and objectives; 1.0; 6.1; 6.2

2. An adaptive management strategy; 6.4; 6.5.1.2; 6.5.1.3;

7.2; 7.3

3. Compliance and effectiveness monitoring; 6.3; 6.3.1- 6.3.4

4. An established permit duration; and 4.2

5. Opportunities for public participation. 4.1.3; 4.1.4

3 Volume 65 of the Federal Register.

12


13

3.0 Description of Areas Analyzed

The geographic area of the HCP is in Central Texas. It is an area rich in the amount and variety of

natural and human resources, but it is undergoing rapid suburbanization associated with burgeoning

growth of the Austin-San Marcos metropolitan area. Land use and cultural aspects are converting

from dominantly rural to dominantly suburban/commercial character (BSEACD, 2017).

Two areas are described in detail in this part of the HCP. The larger is the “Planning Area,” which

includes the entire area that either affects or is affected by the HCP and in which mitigation

measures could take place. The smaller is the “Incidental Take Permit Area,” or ITP Area, which is

coincident with the District’s jurisdictional area for the Aquifer. The ITP Area is where the Covered

Activities of the District take place and where any resulting incidental take of Covered Species

occurs.

3.1 Planning Area

The Planning Area is shown in Figure 3-1. It encompasses the jurisdictional area of the District,

which includes the Barton Springs complex (the four main outlets that together constitute Barton

Springs), and the areas outside the District that contribute recharge to the Aquifer and use the

Aquifer for water supply.

3.1.1 General Environmental Setting of Planning Area

The environmental setting of much of the Planning Area has been described in considerable

detail in the recent Barton Springs Pool HCP that addresses the same Covered Species, and those

descriptions are incorporated herein by reference (City of Austin, 2013). The Barton Springs

Pool HCP can be accessed online at:

http://www.austintexas.gov/watershed_protection/publications/document.cfm?id=203078. This

section is based largely on those descriptions and highlights the aspects of the environmental

setting that are most pertinent to the District’s Covered Activities, the Covered Species, and this

HCP.

3.1.1.1 Physical Environment

The Planning Area is in the southern extension of the North American Great Plains, at the

eastern edge of the large Edwards Plateau region in Central Texas. The Balcones Fault Zone

straddles the boundary between the Edwards Plateau to the north and west and the Gulf Coastal

Plain to the east and south. A number of large springs, including Barton Springs, are at land

surface along the fault zone, where more permeable, older limestone layers are juxtaposed

against less permeable younger layers. Barton Springs is located along and in Barton Creek, a

major tributary just upstream from the Colorado River. Barton is the lowest in elevation of these

springs, and it and the Colorado River form the regional flow boundary for deep, fresh

groundwater that is not discharged at other, higher-elevation springs.

14

Figure 3-1: Planning Area of District Habitat Conservation Plan. The Planning Area comprises the areas shown in color. The District’s overall jurisdictional area is the area bounded

by the black lines. Its jurisdictional area for the Aquifer comprises the area encompassed by the heavy black

boundary in the northern part of the District.

The climate of the Planning Area is classified as subtropical humid, with mild winters and hot

summers. But during multi-year periods, the climate might be considered semi-arid, especially

in western parts of the Hill Country. Heavy rainfall can occur in any month, but generally the

winter months are drier and, at least statistically, the early- and late-summer months are wetter

than average. Rainfall and runoff are highly variable in time and space. The concept of

“average rainfall” is misleading when considered in a predictive sense at any one location, and

there are significant gradients toward smaller rainfall and greater evapotranspiration from

northeast to southwest across the Planning Area. Generally, annual evaporation exceeds annual

rainfall considerably, often by a factor of two or more; the long-term average factor is about 1.6.

Antecedent soil-moisture conditions determine whether and how much rainfall of a given

duration is required to produce runoff to the local streams.

The entire area is prone to drought, which may be severe and persist for months to many years.

Virtually every decade has had one or more significant drought periods that has lasted for a

substantial part of a year or more. The most severe drought in recorded history in the area was

15

the drought during 1950–57, which is designated for water planning purposes as the DOR.

During that drought, Barton Springs had its lowest recorded daily flow, 9.6 cfs (0.27 m3/s), and

its lowest monthly flow, 11 cfs (0.31 m3/s) (See Section 3.2.2.1.2, Sources of Variation in

springflow at Barton Springs). Conversely, the small streams in the Planning Area from time to

time are subject to short-term, sometimes extreme flooding. Such flooding is associated with

tropical moisture systems that move inland and meet the Balcones Escarpment and/or cold air

masses, which produce flooding rainfall intensities. Floods may actually occur in the midst of a

drought, and the storms that cause the floods may or may not relieve the drought, depending on

location of the rainfall and persistence of the drought. During the decade that is designated by

the TWDB as the DOR for this region, there were significant periods when streamflow and

springflow were near average, at least for a while. These variations in rainfall and drought

conditions appreciably affect the natural resilience and ecological health of streams and their

resident flora and fauna (Service, 2013b; Poff and Ward, 1989; Resh et al., 1988).

The Planning Area is drained by two major Texas river systems, with the Colorado River system

tributaries in the northern part and the Guadalupe-Blanco River system tributaries (including the

upper part of the main stem of the Blanco) in the southern part. All surface streams except the

main river stems are non-perennial, although most have base flow (-sustained flow) that is

supported by shallow groundwater contributions during non-drought and non-severe drought

periods. Only the primary river systems have large enough catchment areas (drainage basins) to

support reservoirs for water supply and/or downstream areas that justify flood-control

impoundments. Areas distant from river main stems typically are dependent on wells and

groundwater for reliable and economic water supplies; these include the more rural parts of the

Planning Area.

3.1.1.2 Biological Environment

The Planning Area includes parts of two terrestrial biogeographically defined ecoregions, with

the dissected margin of the Edwards Plateau ecoregion to the west and the southern part of the

Texas Blackland Prairie ecoregion to the east (Texas Parks and Wildlife Department [TPWD],

2012). The rolling topography has level to gently rolling plains in the east and steeply sloping

and dissected uplands in the west. In combination with climate gradients from east to west and

different geology on either side of the Balcones Fault Zone, soil types with varying depths and

textures have been produced, which in turn support diverse vegetation and wildlife.

The Blackland Prairie is a native prairie grassland community that is dominated by a diverse

assortment of perennial and annual grasses. Its dark soil is considered some of the richest soil in

the world and supports an active agricultural community, especially to the north of the Planning

Area. This ecoregion predominately comprises live oak and Ashe juniper, with increasing

amounts of post oak, blackjack oak, American elm, winged elm, cedar elm, sugarberry, green

ash, osage-orange, honey mesquite, and eastern red cedar in the northeastern parts of the

Planning Area. Pecan, black walnut, black willow, American sycamore, honey locust, and bur

oak commonly are in bottomland woodlands throughout this region (Texas Forest Service at

Texas A&M University, 2008).4

4 The scientific names of the common vegetation and wildlife species identified above to characterize various

assemblages are available in the citations referenced. None of them are federally protected species. The federally

16

Common vegetation in the Planning Area (TPWD, 2013) includes:

Switchgrass

Bluestem grass

Grama grass

Indiangrass

Wild rye

Curly mesquite

Buffalograss

Live oak

Shinnery oak

Ashe juniper

Mesquite

Bald cypress

Pecan

Possumhaw

Smartweed

Sugarberry

Boxelder

Buttonbush

Black willow

Marsh purslane

Water pennywort

Cattail

Common wildlife in the Planning Area (TPWD, 2013) includes:

Muskrat

White-tailed deer

Rio Grande turkey

Raccoon

Javelina

Brazilian freetail bat

Ringtail

Nine-banded armadillo

Tarantula

Northern mockingbird

Guadalupe bass

Salamanders (common)

Cricket frog

Gulf Coast toads

Grebes

Blue herons

Green-backed heron

Kingfishers

Both ecoregions are undergoing change as the human population increases. In some areas close

to urban areas, suburbanization is replacing native vegetation with turf grasses, non-native

plants, and impervious cover, and displacing native wildlife. But perhaps the most pervasive and

ecologically significant long-term change for the non-suburbanizing part of the Planning Area is

the purposeful suppression of wildfire. As noted in the Barton Springs Pool HCP (City of

Austin, 2013):

The natural vegetation of the Edwards Plateau uplands is characterized by oak savannas

and grassy terrains, bisected by canyons and riparian areas with thick forest vegetation and

a great diversity of trees and shrubs. The Blackland Prairie was dominated by tall-grass

prairie and deciduous bottomland forest. The savanna and prairie ecosystems were

maintained by fires and grazing bison. With the suppression of fire [as the area has

developed], the openness once characterizing portions of these regions has been severely

reduced. This allowed the encroachment and increase in abundance of species once

controlled by fire, such as Ashe juniper (Juniperus ashei). Natural savanna and tall-grass

prairie are absent in much of both ecoregions today.

protected species are identified by both their common and scientific names in Section 3.2.4, Protected Species in the

ITP Area.

17

The springs along the margins of the Edwards Plateau have their own ecological character. The

smaller, headwater seeps and springs tend to have shallow water, high canopy cover, fast current,

and low nutrient content (City of Austin, 2013; Mabe, 2007). These factors likely result in

naturally low abundance and diversity of aquatic macrophytes (visible plants) and macroalgae

(multicellular algae). The City of Austin (COA) notes that larger springs within wider, higher-

order streams, such as the reach of Barton Creek that contains outlets of Barton Springs, likely

have a greater abundance of aquatic macrophytes than headwater springs because the canopy

cover is less, current is slower, and nutrient load is greater (City of Austin, 2013).

The fauna within the Planning Area are mostly transitional (Abell et al., 1999). Although the

Edwards Plateau is home to more than 100 fish species, few of them are endemic (found only in

a specific location). In contrast, many endemic aquatic fauna are in spring-fed streams of the

Edwards Plateau. More information on the vegetation and fauna specifically associated with the

Barton Springs complex is in Section 3.2.2.2, Ecological Setting.

A summary listing of the plant and animal species that the TPWD considers to be in greatest

need of conservation is in Appendix A, with separate tables for the Edwards Plateau and Texas

Blackland Prairie ecoregions. Federally protected species of potential interest specifically to this

HCP also are identified and discussed as to their relationship to the proposed Covered Activities

in Section 3.2.4, Protected Species in the ITP Area.

3.1.1.3 Man-made Environment

The Planning Area is on the suburban fringes of the Austin-San Marcos Metropolitan Statistical

Area, which includes Austin, Buda, Kyle, and San Marcos, all of which are undergoing rapid

growth that extends into the Planning Area. The current (2014) population of this area has been

estimated by the District, on the basis of geospatial analysis of the latest census data, to be

583,000. It is expected to increase to more than 800,000 during the proposed 20-year term of the

ITP, using conservative growth-rate projections in the ongoing regional water-resource planning

by the TWDB:

Planning Horizon Population in HCP Planning Area

2010 Census 525,000

2015 (Start of ITP) 583,000

2035 (End of ITP) 803,000

2040 855,000

The COA has indicated that much of the population increase in the Colorado River basin part of

the Planning Area will occur in the Barton and Williamson Creek watersheds (City of Austin,

2013). Growth associated with the Cities of Kyle and San Marcos in the Planning Area will

largely be in the Plum Creek and Blanco River watersheds of the Guadalupe-Blanco River basin.

The more western and eastern parts of the Planning Area will continue to be mostly rural,

although some areas near transportation corridors and communities outside of suburbs will

increasingly become rural residential and commercial.

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Much of the firm-yield water supply (water that will be physically available and that is

authorized for use during all hydrologic conditions, including Extreme Drought) throughout the

Planning Area is fully subscribed, including supplies of fresh groundwater from the Aquifer. For

this reason, the accuracy and precision of future population estimates are not particularly

germane to future demand for existing water supplies in the Planning Area. Public water-supply

(PWS) systems are now actively pursuing alternative surface-water and groundwater supplies

from outside the Planning Area to serve their projected growth. Consequently, the number of

people who are now provided groundwater from the Aquifer is not expected to increase

significantly from the current 70,000 estimate; in fact it may decrease as smaller PWS systems

using the Aquifer are subsumed by and become part of larger systems on alternative supplies.

The population growth that takes place in areas that are outside the various municipal limits will

create wastewater treatment and disposal challenges that may have adverse effects on water

quality. Increasing use of centralized wastewater treatment systems that directly discharge even

highly treated wastewater into small streams upstream from the Recharge Zone is likely, along

with continued proliferation elsewhere of land-application systems and septic tanks. These

facilities have the potential for surface-water and groundwater quality degradation if they are not

adequately sited, designed, and/or maintained.

3.1.2 Hydrogeologic Framework of Planning Area

An understanding of the hydrogeologic framework supports the District HCP. The detail

provided in this subsection is required to establish and monitor effectiveness of suitable

conservation measures for the Covered Species.

The only known habitat for the Covered Species is groundwater in the Aquifer, including but not

limited to the well-documented natural discharges from the Aquifer at the four Barton Springs

outlets5 (the multiple sub-outlets of Main Springs [Parthenia Spring] in Barton Springs Pool,

Eliza (Concession) Spring, Old Mill [Sunken Garden, or Zenobia] Spring, and Upper Barton

Spring); their associated surface spring runs; and the subterranean (underground) areas of the

Barton Springs complex. These outlets, which are described in more detail in Section 3.2.2.1.1,

Physical Characteristics of Barton Springs, are the primary points of freshwater discharge from

the Aquifer. So water passing into and through Barton Springs comes primarily from the

Aquifer, although also occasionally and transiently from a flooding Barton Creek.

The Aquifer is a karst aquifer, characterized by features such as caves, sinkholes, sinking streams

(streams that lose water to an aquifer), springs, and other conduits that have been enlarged by

dissolution of the host carbonate rock (Woodruff and Abbott, 1979). The Aquifer also is in an

area with extensive, complex faulting and fracturing, which provide the potential for additional

hydrologic interconnections.

5 Throughout this HCP, the District designates the specific outlets of the Barton Springs complex by the following

names: Main Springs (which in this HCP actually refers to closely associated, multiple sub-outlets within Barton

Springs Pool), Eliza Spring, Old Mill Spring, and Upper Barton Spring. All of these have alternative names, shown

here in parentheses or brackets, which are sometimes used by various other entities. There is no standard usage.

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3.1.2.1 Aquifers and Hydrozones

The near-surface hydrogeology of the Planning Area is dominated by two karst aquifers

associated with the Balcones Fault Zone: the Edwards Aquifer, and the Trinity Aquifer. These

aquifers, primarily the Edwards, are central to the need for and development of the HCP.

The Edwards Aquifer is composed of Cretaceous-age limestones and dolomites of the Edwards

Group (Rose, 1972). At the regional level, the Edwards Aquifer has three segments, commonly

referred to as the San Antonio (or Southern) segment, the Barton Springs segment, and the

Northern segment. The San Antonio segment and the Barton Springs segment are separated by a

groundwater divide, and the Barton Springs segment and the Northern segment are separated by

the Colorado River (Figure 3-2). The freshwater part of the Barton Springs segment that

contributes to the habitat for the Covered Species covers about 170 square miles (440 square km)

(Slade et al., 1986). The hydrologic region that influences the Aquifer and therefore the District

HCP (Planning Area, Figure 3-1), comprises the Aquifer’s Contributing Zone, Recharge Zone,

Confined Zone, and Saline Zone in Central Texas. Most of the HCP Planning Area is in

northern Hays and southern Travis Counties. Smaller parts of the Planning Area extend into

Bastrop, Blanco, Caldwell, Comal, and Kendall Counties.

The freshwater part of the Barton Springs segment consists of two major zones: (1) the Recharge

Zone, where rocks of the Aquifer are exposed and hydrologically unconfined6; and (2) the

Confined Zone, where the Aquifer is overlain by other rock units (such as clay) and generally is

hydrologically confined. There is a transitional area between the two zones where the

hydrologic conditions (confined vs unconfined) can vary depending upon drought or non-

drought conditions (Slade et al., 1986).

The Recharge Zone as defined herein covers about 107 square miles (277 square km) of the

Planning Area (Figure 3-1). Recharge is the process by which water enters and replenishes an

aquifer. Most recharge to the Aquifer is derived from streams originating in the Contributing

Zone, up gradient and generally west of the Recharge Zone. Water flowing onto the Recharge

Zone sinks into numerous caves, sinkholes, and fractures along numerous (ephemeral [briefly

flowing] to intermittent [periodically flowing]) streams (Slade et al., 1986). For the Barton

Springs segment, Slade (2014) estimated that as much as 75% of recharge to the aquifer is from

water flowing in these streams. The remaining recharge (25%) occurs as infiltration through

soils or direct flow into discrete recharge features in the upland areas of the Recharge Zone

(Slade, 2014). Hauwert and Sharp (2014), building on investigations by Hauwert (2009, 2011)

estimate that recharge in the uplands (autogenic) is about 28% under average rainfall conditions.

Under higher than average rainfall, autogenic recharge can be as high as 30-45% of precipitation

(Hauwert and Sharp, 2014). These studies recognize that a significant amount of recharge to the

Edwards Aquifer is from flow in the creeks that cross the Recharge Zone. Additional potential

sources of inflows and recharge to the Aquifer are discussed in section 3.2.2.1.2. Sources and

Implications of Variation in Springflow at Barton Springs.

6 Unconfined aquifers or zones are not overlain by relatively impermeable rock unit(s). Water levels in tightly cased

wells in unconfined units are below the top of the aquifer or hydrozone (unless the land surface is flooded). Confined

aquifers or zones are overlain by relatively impermeable rock unit(s). Water levels in tightly cased wells in confined

units are above the top of the aquifer or zone and are above land surface where springs flow.

20

Mean surface recharge to the Barton Springs segment of the Edwards Aquifer should be

approximately equivalent to the more directly measured mean flow, or about 53 cfs (1.5 m3/s) for

the period of record (Scanlon et al., 2001). Climatic changes since the 1960s indicate the mean

flows are about 65 cfs (1.8 m3/s; Hunt et al., 2012b), and even higher if you consider total

discharge (which includes pumping). Recharge is highly variable in space and time and focused

within discrete features (Smith et al., 2001). It is estimated that maximum recharge during

flooding may approach 400 cfs (11 m3/s) (Slade et al., 1986). For example, Onion Creek is the

largest contributor of recharge to the Barton Springs segment (34% of total creek recharge) with

maximum recharge as much as 160 cfs (4.5 m3/s; Slade et al., 1986). Antioch Cave, which is in

the Onion Creek channel, is the largest-capacity discrete recharge feature known in the Barton

Springs segment, with an average recharge of 46 cfs (1.3 m3/s) and a maximum of 95 cfs (2.7

m3/s) during a 100-day period (Fieseler, 1998). A more recent study (Smith et al., 2011)

estimates that Antioch Cave in the bed of Onion Creek is capable of recharging as much as 100

cfs (2.8 m3/s) from that part of Onion Creek upstream from Antioch Cave. The District

constructed and operated, under an Environmental Protection Agency grant program, a recharge

enhancement facility at Antioch Cave (the Antioch Recharge Enhancement Facility) to preserve

and increase recharge to the Aquifer derived from this discrete feature; the facility currently

continues to be maintained by the District. This facility reduces the problematic “first-flush” of

sediments that clog voids and the accompanying pollutants that enter the Aquifer as runoff from

a developing watershed, thereby helping sustain the quantity of recharge as well as improve its

water quality.

Protection from adverse effects of storm runoff and conservation of streamflow in the watersheds

of these creeks are important to maintaining the water quality and chemistry of the habitat at

Barton Springs (Service, 2005). The Recharge Zone has numerous wells, many of them low-

capacity individual household supply (domestic-use) wells and also a few large-capacity wells,

especially where the saturated thickness of the Aquifer is relatively large and is able to supply

relatively large amounts of water without being overly susceptible to drought impacts.

The Confined Zone generally is fully saturated. This 59-square-mile (153-square-km) area is

where most groundwater withdrawal occurs (Figure 3-1). The Confined Zone comprises a

continually confined part, which is farther from the Recharge Zone, and an intermediately

confined, transitional part closer to the Recharge Zone that varies between unconfined and

confined conditions, depending on water levels in the Aquifer. Some areas immediately east of

the Recharge Zone are unsaturated to variable depths below the overlying low-permeability

units. In the Confined Zone, dipping and faulted impermeable layers of clay and other less-

permeable rocks overlie the Aquifer, which becomes progressively deeper with distance

eastward. Aquifer conditions in the Confined Zone thus transition from intermediately confined

to continually confined with distance eastward. Because much of the water moving through the

Aquifer is under pressure in dissolution cavities and conduits that transport water from higher

elevations, areas of the Aquifer near springs show both unconfined and confined characteristics,

depending on water levels in the Aquifer7 (Wong et al., 2012). Accordingly, the Barton Springs

complex can be considered a hybrid (gravity and artesian) spring complex.

7"Unconfined characteristics" implies water levels in the Aquifer are below the top of the aquifer. "Confined

characteristics" implies water levels in the Aquifer are above the top of the aquifer. At spring outlets, the elevation of

land surface is below the elevation of the water level in the Aquifer, hence water flows from the outlet.

21

Upstream from the Aquifer is the Contributing Zone, which contributes surface runoff and base

flow of streams to the Aquifer but is not considered a part of the Aquifer (Figure 3-1). The

Contributing Zone spans about 671 square miles (1,738 square km) of the Planning Area and

includes parts of Travis, Hays, Blanco, Kendall, and Comal Counties. What has been

historically designated as the Contributing Zone during all hydrologic conditions encompasses

the upper watersheds of the six major creeks that cross the Recharge Zone. However, this

definition excludes the upper Blanco River watershed that recent studies (Smith et al., 2012a;

Casteel et al., 2012; Smith et al., 2014) have shown to be a contributor of recharge to the Aquifer

during drought conditions. Although the six creeks in this area are the source for most of the

water that enters the aquifer as recharge, the Blanco River is an important contributor during

severe drought conditions. The Recharge and Contributing Zones together make up the total

area that provides meteoric water (water that is derived from relatively recent precipitation on

land surface) to the Aquifer.

The eastern boundary of the Aquifer is the interface between the freshwater zone and the Saline

Zone (sometimes referred to as the “bad-water” zone) of the aquifer, characterized by a sharp

increase in dissolved constituents (more than 1,000 mg/L total dissolved solids [TDS]) and a

decrease in permeability (Flores, 1990). The Saline Zone has groundwater that ranges from

brackish (greater than 1,000 mg/L TDS) to saline (greater than 10,000 mg/L TDS). Hunt et al.,

(2014) provides a delineation of the boundary for the planning area based on new groundwater

chemistry data. The report summarizes many previous studies and concludes that the interface

appears to be relatively stable over time in the Barton Springs segment of the Edwards Aquifer.

Although encroachment does not appear to be a threat to freshwater supplies, changes in the

springflow chemistry at Barton Springs suggest some leakage (flow) into the freshwater aquifer

under drought conditions (Hunt et al., 2014).

The Trinity Aquifer underlies the Recharge, Confined, and Saline Zones of the Aquifer. The

Trinity Aquifer is also a karst aquifer but with much more variable yield (in this context, the

limiting rate at which groundwater is capable of entering a well bore) and water chemistry than

the Edwards Aquifer, owing to its rock characteristics. The Trinity Aquifer crops out across the

entire Contributing Zone and provides base flow to the larger streams there that eventually

recharge the Edwards. In addition, the uppermost part of the Trinity Aquifer and the Edwards

Aquifer are hydrologically connected (allows exchange of water between units) (Wong et al.,

2014), and in some places the Trinity probably contributes flow to the Edwards and vice versa,

depending on their respective water-level elevations. Recent studies (Wong et al., 2014; Smith

and Hunt, 2011) have shown that the Edwards Aquifer is not hydrologically connected to the

deeper units of the Trinity Aquifer.

3.1.2.2 Groundwater Flow Conditions

In the Recharge Zone, meteoric water moves vertically from the land surface into the Aquifer

through faults, fractures, and dissolution features in streambeds and less dominantly via soil

infiltration in the karstic uplands. After reaching the water table, it then moves more laterally

through the Aquifer via groundwater flow paths inside caverns, conduits, and other dissolution

features that differ in size. Groundwater movement in the western part of the Aquifer is

22

Figure 3-2: Locations of Groundwater Flow Paths and Covered Species Habitat in the Barton Springs

segment of the Edwards Aquifer. Approximate locations of groundwater flow paths, known habitat of Covered Species, and the hydrologic divide that

separates the San Antonio segment from the Barton Springs segment of the Edwards Aquifer are shown. The

Colorado River hydrologically separates the Barton Springs segment from the Northern segment of the Edwards

Aquifer.

23

generally to the east and then north (Figure 3-2). Groundwater levels throughout the Aquifer are

highly interrelated and, in many areas, correlate well with springflow at Barton Springs (Smith

and Hunt, 2004). These flow routes are presumed to support subterranean habitat for at least the

Barton Springs salamander, if not both Covered Species, because the known locations of the

salamander appear associated with primary and secondary flow routes, as shown in Figure 3-2.

Runoff flowing across the Recharge Zone and entering the Aquifer reaches the water table

quickly. And groundwater flow velocities in the Aquifer are very rapid (Hauwert, 2009;

Hauwert et al., 2004; BSEACD, 2003). Groundwater-tracing studies have delineated several

major groundwater flow routes and have been used to measure groundwater velocities. The

major flow routes transmit water derived from different contributing sources, including relatively

new recharge, water moving into and out of storage, older recharge from areas distant from

Barton Springs, and interformational flow (flow between geologic units, or formations) of

differing characteristics, including the saline part of the Edwards (Mahler and Bourgeais, 2013;

Johns, 2006). The flow rates of groundwater along the dominant flow paths range from about 1

mile (1.6 km) per day under low groundwater flow conditions to about 5 miles (8 km) per day

under moderate to high groundwater flow conditions (BSEACD, 2003). The rapid hydrologic

response of the Aquifer to precipitation and surface runoff emphasizes the importance of

protecting the quality and quantity of water in each of the six major creeks, and the Blanco

River, in conserving the habitats of the Covered Species (Johns, 2006; Service, 2005; Hauwert et

al., 2004).

The rate at which groundwater discharges at Barton Springs8 depends directly on water levels in

the Aquifer. Under drought conditions, surface flow in the Contributing Zone creeks ceases, and

Aquifer water levels decrease as water is discharged from the Aquifer at pumping wells and

spring outlets. Flow from small spring outlets at relatively high elevations, such as Upper Barton

Spring ceases for extended periods, and flow from the main outlets decreases. At low water

levels in the Aquifer, less groundwater flows solely (although rapidly) through large conduits.

In the immediate vicinity of the Aquifer’s major discharge at Barton Springs, periods of high and

low flow have been a natural characteristic of the Barton Springs/Barton Creek ecosystem (City

of Austin, 2013, 2007a, 2007b, 2006, 1997). Presently, the dam and other constructed

infrastructure creating Barton Springs Pool inhibit the beneficial flushing of sediment and debris

provided by shallow, free-flowing water from the spring outlets and the creek. For a given flow,

shallow streams and creeks have greater flow velocities and consequently, stronger natural

cleansing power. In addition, disturbance by episodic flooding is an important feature of streams

and rivers (Gordon et al., 2004 and references therein; Poff and Ward, 1989; Resh et al., 1988)

and was a natural characteristic of the Barton Springs complex before alteration by humans

beginning in the late 1800s. Conversely, the Pool elevation is higher than Eliza Spring, with

which it is in hydrologic communication, and discharge from Eliza is at least partially dependent

8Rates of streamflow and springflow are conventionally expressed as cubic feet per second, or “cfs.” Rates of

groundwater use and overall production from an aquifer are usually expressed in acre-feet (AF) per unit time, typically

per year. Groundwater withdrawal from individual wells is usually expressed in gallons per minute or thousand gallons

per day. The District’s permits are issued in terms of gallons per year. To facilitate comparisons of discharges from

wells and springs, the District uses “cfs” for both in this HCP. 1.00 cfs = 723 AF per year. 1000 AF per year = 325.9

million gallons per year = 892,700 gallons per day. 1.00 cfs = 0.0283 cubic meters per second (m3/s),

24

upon the Pool elevation at all times. The District has no authority or control over the physical

conditions and maintenance of the surface-water system that could affect the creeks and spring

outlets.

Dye-tracing studies (BSEACD, 2003; Hauwert et al., 2004), direct flow measurements of the

individual outlets that are statistically correlated with combined spring flow (City of Austin,

2013), and outcomes of human-controlled, pool-drawdown events have shown that the spring

outlets of Barton Springs are hydrologically related, particularly Main Springs and Eliza Spring.

These analyses indicate that any factor that causes a change in water quantity at one spring outlet

also has the ability to affect water quantity at the other spring outlets at Barton Springs (Service,

2005).

3.1.3 Barton Springs/Edwards Aquifer Conservation District

Jurisdictional Area

The District’s total jurisdictional area, bounded in black in Figure 3-1, is shown in more detail in

Figure 3-3. This area is statutorily established and delineates the area where the District’s rules

and regulations are enforceable. As a result of legislation passed in 2015, this area became

significantly larger, now totaling about 418 square miles, because the District annexed an

additional portion of Hays County where the Trinity Aquifer was not regulated by any

groundwater conservation district. The newly annexed area, designated “Shared Territory” in

Figures 3-1 and 3-3, does not have any part of the Barton Springs segment of the Edwards

Aquifer underlying it; where the Edwards is present in this area, it is the San Antonio segment of

the Edwards, which is regulated solely by the Edwards Aquifer Authority. The District’s

jurisdiction in the Shared Territory excludes the Edwards Aquifer and includes all other aquifers,

including the underlying Trinity. The jurisdictional area that existed before the 2015 annexation

is designated in this HCP and on Figures 3-1 and 3-3 as the “Exclusive Territory” and comprises

about 255 square miles in northwestern Caldwell, northeastern Hays, and southeastern Travis

Counties. The boundary of this Exclusive Territory approximates the hydrogeologic boundaries

of the Aquifer in places, and in others, follows certain boundaries of the service areas of several

public water supply (PWS) utilities as they existed when the District was formed in 1987.

Under its enabling legislation, the District’s jurisdiction in the Exclusive Territory is defined by

metes and bounds (system of describing land using physical features, directions, and distances)

to approximate a combination of natural and man-made boundaries. On the west, the boundary

was drawn to approximate the location of the western edge of the Edwards Aquifer outcrop, and

on the north by the Colorado River. The eastern boundary is generally formed by what were the

easternmost service area limits, at the time the District was formed in 1987, of what are now the

Creedmoor-Maha Water Supply Corporation, Monarch Utilities/Southwest Water Company, and

Goforth Special Utility District. Changes made in those other entities’ boundaries since then

have not changed the District’s boundaries. (In 2009, the District legislatively de-annexed a

small part of the service area of one of these utilities in Bastrop County, which is now outside the

District.) The District’s southwestern and southern boundary of the Exclusive Territory is

generally established in alignment with the approximate average position of the groundwater

divide between the Barton Springs and the San Antonio segments of the Edwards Aquifer

(Figure 3-2). To the southeast, the boundary is along the southernmost service-area boundaries

of several water-supply utilities, including Goforth (the District permittee with the largest

25

authorized use, at 351 million gallons (1.33 billion liters) per year) and Monarch Utilities,

another large Aquifer user. So, by original design, the District’s jurisdictional boundaries in the

Exclusive Territory have been aligned with the area where the Aquifer is used as a water supply.

Some of the Aquifer water withdrawn within the District is physically transported by pipeline to

other parts of the District and to nearby areas outside the District. The native groundwater

(water that occurs naturally within an aquifer without influence from pumping or other

anthropogenic [human-caused] activities) in the eastern part of the District’s jurisdiction is

brackish to saline, and therefore it is generally unsuitable as a potable water supply without

expensive treatment. Freshwater supplies to this area are provided by Edwards wells west of

Interstate Highway 35 and transported to customers of those water utilities by various water

suppliers that are District permittees. (Other water sources also supply this area.) Also, a single

well in the extreme southern part of the District’s Exclusive Territory is the most prolific single

Aquifer well in the District, providing a large amount of water that is exported from the District

to the City of Kyle, just outside the District’s jurisdictional boundary. However, the well is

within the District, and thus Kyle is one the District’s largest permittees (350 million gallons

(1.33 billion liters) per year).

The District regulates groundwater from all aquifers underlying its Exclusive Territory and from

all aquifers except the Edwards in its Shared Territory. An increasing amount of groundwater

from the Trinity Aquifer, especially the middle and lower zones of the Trinity Aquifer

(commonly called the Middle and Lower Trinity Aquifers, respectively), is now being used in

the jurisdictional area as an alternative supply to the Edwards and is also managed by the

District.

3.2 Incidental Take Permit Area

The ITP Area comprises (a) the subsurface part of the Exclusive Territory of the District where

groundwater in the Aquifer is encountered by wells, and (b) the spring outlets area, where

groundwater changes to surface water at the Aquifer’s primary natural outlets at Barton Springs.

The ITP Area defines where take may occur from time to time, where the Covered Activities are

expected to be authorized under the ITP, and where conservation measures will be implemented.

All the wells in the Aquifer are located in the ITP Area.

3.2.1 Subsurface Part of District’s Exclusive Territory

The subsurface part of the Exclusive Territory within the District’s jurisdiction (Figures 3-1,

Figure 3-3) is hydrogeologically and geographically the ITP Area, and both are part of the

Planning Area. This area, described in Section 3.1.2, Hydrogeologic Framework of the Planning

Area, is composed of the Aquifer and its groundwater flow system that provides water to Barton

Springs. It is within the District’s jurisdictional area that its rules and regulations for

groundwater management apply.

The Edwards Aquifer in the southernmost part of the Planning Area (parts of the Recharge Zone

and Confined Zone in the Shared Territory in Figures 3-1 and 3-3), is regulated by the Edwards

26

Aquifer Authority (EAA) in San Antonio. The subsurface part of the aquifer in this area is not

included in the District’s ITP Area. It is included in EAA’s HCP (Edwards Aquifer Recovery

Implementation Plan) and ITP Area (EARIP, 2012).

Figure 3-3: Barton Springs/Edwards Aquifer Conservation District Jurisdictional Area. The District has different regulatory authorities in the Shared Territory and the Exclusive Territory. The Exclusive Territory is coincident with the ITP Area. Source: BSEACD (2015).

27

3.2.2 Spring Outlets Area

3.2.2.1 Physical Setting

3.2.2.1.1 Physical Characteristics of Barton Springs

The ITP Area includes the submerged surface rocks and underlying shallow subsurface rocks in

the immediate vicinity of the individual springs that together constitute the Barton Springs

complex. The complex comprises Main Springs, which is impounded to form Barton Springs

Pool; Upper Barton Spring; Eliza Spring; and Old Mill Spring (Figure 3-4). Incidental take of

Covered Species in this springs complex would be expected to occur in the submerged areas in,

below, or just beyond the individual spring outlets, which are the primary natural discharge

points of the Aquifer and are the best documented habitats of the Covered Species. The black

line in Figure 3-4 circumscribing the outlets delineates the inferred area of potential surface and

subterranean habitat and subterranean migration zones for the Barton Springs salamander in the

Barton Springs complex, and the area within the black line is the ITP Area for the Barton Springs

Pool HCP. As such, it also delineates the inferred habitat area of the Austin blind salamander for

that HCP. The yellow lines represent the perimeters of protected salamander habitat at each

spring site. Previously, the surface outflow stream from Eliza Spring was contained within a

buried pipe, which has until now carried water from Eliza in the subsurface directly into the

Barton Springs Pool bypass culvert. But the COA is restoring the spring run at Eliza to more

natural conditions (the Eliza Spring Daylighting Project), and the project was substantially

completed in the fall 2017.

The localized part of the District ITP Area that encompasses the spring outlets is thus in the

Barton Springs Pool ITP Area. While the District HCP covers the same Covered Species as the

Barton Springs Pool HCP, the Barton Springs Pool HCP covers impacts by recreational use

(swimming, diving, wading) and maintenance operations (cleaning, caretaking, lowering) of the

Pool, and work in the spring outlet areas, including areas of surface flow from the outlets. A

detailed description of the habitats at the spring outlets is excerpted from the Barton Springs Pool

HCP and provided as Appendix C. The COA owns the land where the individual spring outlets

are, and under its HCP, maintains and operates all man-made structural elements around the

spring outlets, including the Barton Springs Pool dam, impoundment, and bypass culvert. The

District does not control access to or operate and maintain any part of the infrastructure at Barton

Springs. Its groundwater management activities only affect, within limits, the amount of water

issuing from the spring outlets and the chemistry of that water as related to and affected by the

rate of discharge.

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Figure 3-4: Incidental Take Permit Area of the COA’s Barton Springs Pool Habitat Conservation

Plan. The area within the black line is the ITP Area for the Barton Springs Pool HCP. The yellow areas denote protected

surface habitat of the Covered Species. Note that Main Spring is also known as Parthenia Spring. Source: City of

Austin (2013).

3.2.2.1.2 Sources and Implications of Variation in Springflow at Barton Springs

The primary threat to the Covered Species and their ecosystems — habitat changes accompanying

low Aquifer water levels and springflow — is affected by the District’s Covered Activities during

drought conditions in the Aquifer and at Barton Springs (Service, 2013b). Variable springflow

conditions are the norm, for which the Covered Species appear to be well suited. Cleaveland

(2006) concludes on the basis of regional dendrochronological (tree-ring dating) studies that

droughts substantially more severe and prolonged than the drought of the 1950s have been a part of

the prehistorical record. But increasing frequency of severe droughts and flash floods also appear

to be the “new normal” (IPCC, 2013), which will continue to challenge and stress salamander

populations.

The long-term (1917–2000) mean springflows at Barton Springs outlets, based on U.S. Geological

Survey (USGS) data for combined springflows from the Barton Springs complex (Main Springs

within the Pool, Eliza Spring, and Old Mill Spring; Upper Barton Spring is not included in these

flows) was 53 cfs (1.5 m3/s; Scanlon et al., 2001). In the more recent period since 1960, the mean

29

springflow was 65 cfs (1.8 m3/s; Hunt et al., 2012b). However, springflow has varied by nearly 17-

fold from extreme low-flow to extreme high-flow conditions. The lowest daily flow recorded at

Barton Springs was about 10 cfs (0.28 m3/s) during the record drought in the 1950s (Smith and

Hunt 2004), and the highest-recorded daily mean flow was 166 cfs (4.70 m3/s; Slade et al., 1986).

The lowest daily mean value of the recent severe drought of 2008–09 was about 13 cfs (0.37 m3/s)

on July 21, 2009 (U.S. Geological Survey, 2010). The data from the same USGS gaging station

showed that the more recent 2011 and 2013 severe droughts caused lowest daily mean flows of

about 16 to 17 cfs (0.45-.48 m3/s). There is considerable uncertainty (as much as ±3 to 4 cfs; 0.085-

0.11 m3/s) in measuring very low flows owing to the measurement approaches and tools available

(Hunt et al., 2012a).

Pumping from the Aquifer does not cause the wide variation in springflow; such variation is

natural. This is illustrated by Figure 3-5, which is a "synthetic" hydrograph of springflow at Barton

Springs; that is, springflow that would have existed naturally, without any pumping from the

Aquifer, for the period of historical record, 1917–2013. This synthetic hydrograph was constructed

using measured (for later parts of the period) and inferred (for certain earlier parts of the period)

monthly springflow and pumpage data. Statistical analysis of the hydrograph, after conversion to a

nonexceedance frequency distribution (graph that shows the percentage of time, or probability, that

a given springflow is not exceeded), yields the relationships shown in Table 3-1. Table 3-1 shows

the percentage of time that several springflows of importance to drought management (discussed

further in Section 4.1.2, Historical Perspective of Covered Activities), under a condition of no

pumpage, would not be exceeded.

Figure 3-5: Reconstructed combined daily flows at Barton Springs under a condition of no pumpage,

1917–2013. Springflow reflects the many wet and dry periods in the Planning Area over the period of record, which cause

springflow to typically be above or below its long-term average of 53 cfs. The populations of the Covered Species have

evolved and adapted to these natural fluctuations in flow and accompanying changes in water chemistry.

30

Table 3-1: Recurrence (nonexceedance) frequencies of natural (no Aquifer pumpage) springflow for

specified drought management thresholds. Frequencies are based on the 1917–2013 period of record, and the thresholds are those currently (2017) used by the

District for managing groundwater.

Aquifer Condition

Total Flow at Barton Springs (cfs)

Percentage of Time Flow Not Exceeded

Average Flow 53 52

Stage II –Alarm Drought 38 36

Stage III – Critical Drought 20 9

Stage IV – Exceptional Drought 14 2

Emergency Response Period 10 <0.01

Regulated Minimum* 6.5** 0

No Springflow 0** 0 * Desired Future Condition, refer to Section 4.1.2, Historical Perspective of Covered Activities.

** Never observed in recorded history.

This analysis shows that even without any nonexempt pumping (pumping subject to the District’s

permitting program), the Aquifer would be in a District-declared groundwater drought status,

designated by the onset of Stage II-Alarm Drought, more than one-third (36%) of the time, and in a

Stage III-Critical Drought almost 10% of the time. The computed frequencies for these threshold

flows, called recurrence or nonexceedance frequencies (percentage of time flow is below a

designated rate), are calculated using monthly data, as pumping records used to construct the

hydrograph are not reported on a more frequent basis. The recurrence frequencies thus correspond

to springflow expressed as a monthly mean (monthly flow duration), and daily mean or

instantaneous springflow will be somewhat larger or smaller. But during a prolonged, severe

drought, with no stormflow, the natural flow of Barton Springs changes very slowly day to day and

week to week (Smith and Hunt, 2004). Accordingly, the recurrence frequencies for monthly mean

flows would be very similar to those for weekly mean or even daily mean flows during such times.

Flow at Barton Springs decreases as aquifer water levels decrease and the amount of groundwater in

storage in the Aquifer decreases. Large decreases in water levels and storage generally have been

caused by climate-related, prolonged periods of rainfall deficit rather than groundwater withdrawal.

Such periods reduce the amount of water recharging the aquifer for extended periods of time. This

is illustrated by the recent, multi-year hydrograph for Barton Springs flow in Figure 3-6, where the

range in springflow in any one drought cycle (about 100 cfs; 2.83 m3/s) is roughly an order of

magnitude larger than the amount of groundwater withdrawn during those times (about 10 cfs; 0.28

m3/s).

However, increased groundwater withdrawal will reduce the quantity of water in the aquifer and

therefore springflow (Scanlon et al., 2001; Smith and Hunt, 2004). More than 1,200 active wells

supply water for public, domestic, industrial, commercial, irrigation, recreational, and agricultural

uses (Hunt et al., 2006). As described in more detail in Section 4.1.1, The Regulated Groundwater

Community, only about 10% of these wells are regulated; but those regulated wells account for

about 96% of the total volume of water withdrawn from the Aquifer (Smith et al., 2013; Smith and

Hunt, 2004).

31

It is important to consider how future groundwater withdrawals will cause variations in Aquifer

water levels and especially springflow, particularly during future droughts. Groundwater flow

modeling by Scanlon et al. (2001) indicated springflow at Barton Springs could possibly cease as

pumping in the Aquifer reaches about 10 cfs. In 2004, the BSEACD did additional modeling to

estimate the “sustainable yield” of water in the Barton Springs segment of the Aquifer based

specifically on the possible recurrence of the DOR (Smith and Hunt, 2004, included herein as

Appendix B). The BSEACD defined sustainable yield then as:

“the amount of water that can be pumped for beneficial use from the aquifer under

drought-of-record conditions after considering adequate water levels in water-supply

wells and degradation of water quality that could result from low water levels and low

spring discharge” (Smith and Hunt, 2004).

Figure 3-6: Variable flow at Barton Springs, September 2006–October 2014. Drought stage thresholds that have groundwater management significance are indicated. Source: BSEACD.

In that study, the BSEACD recalibrated the model used by Scanlon et al. (2001) to more accurately

predict springflow and water level declines under DOR conditions. Withdrawals were projected for

future years. This first-ever, rigorous assessment of the sustainable yield of the Aquifer

(Sustainable Yield Study) showed that the then-authorized pumpage of the Aquifer, about 10.2 cfs

(0.289 m3/s), equivalent to 2.41 billion gallons (9,120 million liters) per year, was essentially its

0

20

40

60

80

100

120

140

10/10/06 10/10/07 10/9/08 10/9/09 10/9/10 10/9/11 10/8/12 10/8/13 10/8/14

Flo

w (

cfs

)

Daily Springflow

10-day average Springflow

USGS Manual Measurements

BSEACD Manual Measurements

COA Manual Measurements

Critical Stage: 20 cfs

Alarm Stage: 38 cfs

Average: 53 cfs

Exceptional Stage: 14 cfs

Emergency Response Period: 10 cfs

32

sustainable yield, as that level of pumping during a recurrence of the DOR, if un-curtailed, would

reduce springflow at Barton Springs to less than 1 cfs (0.028 m3/s) and would cause some 19% of

the wells in the shallower part of the Aquifer to have substantial yield problems from declining

water levels in wells. More specifically, the recalibrated model indicated that under DOR

conditions, the then-current pumpage of about 10.2 cfs would result in a monthly mean springflow

of about 1 cfs for about 1 month. It also indicated that under continuous DOR conditions, projected

withdrawals of 15 cfs (0.42 m3/s), if un-curtailed, would cause Barton Springs to cease flowing for

at least 4 months (Smith and Hunt, 2004).

The Sustainable Yield Study was the impetus for rulemaking that established the District’s

conditional-use (interruptible-supply) permitting program for Aquifer permit applications initiated

after September 2004. This study also demonstrated the one-to-one correspondence between

changes in pumped volumes and changes in springflow during Extreme Drought conditions (Smith

and Hunt, 2004). Taken together, these findings ultimately formed the basis of the groundwater

availability modeling for establishing modeled available groundwater (MAG) amounts related to

the adopted Extreme Drought Desired Future Condition (DFC) of the Aquifer, which balances

maintaining ecological habitat and well yields with being able to enforce as stringent curtailments

as practicably possible.

At the time of the Sustainable Yield Study, the biological needs of the Covered Species were not

explicitly and quantitatively addressed, other than the general recognition that nearly total cessation

of springflow was not acceptable on ecological grounds. But the results of the numerical

simulations had considerable implications for the Covered Species and their habitat. They

suggested that, if Central Texas again experiences drought conditions similar to those of the 1950s,

without active groundwater management, the viability of the species could be imperiled by

critically low or no flow at spring outlets. In that circumstance, low flow at Barton Springs could

cause substantial habitat degradation and a loss of plant and animal life (City of Austin, 2013).

These effects and their consequences are characterized in more detail in Section 5.2.4, Effects of

Take on Covered Species.

Numerous effects of low flow have been observed in various parts of the Barton Springs complex

(City of Austin, 2013). Upper Barton Spring ceases to flow when the combined discharge from the

Barton Springs complex is about 40 cfs (1.1 m3/s). Old Mill Spring experiences a relatively sharp

decrease in DO concentration at about 20 cfs (0.57 m3/s) combined springflow and ultimately a

virtual cessation of flow at lower flow (about 14 cfs) (0.40 m3/s; City of Austin, 2013; Turner,

2004b). Also, the COA discovered that Eliza Spring ceases to flow when the dam gates in Barton

Springs Pool are opened and water is drawn down during periods of low springflow, which

previously stranded and killed some salamanders. To prevent Eliza Spring from going dry while it

is in its current configuration, water in Barton Springs Pool is no longer drawn down when

combined flows are less than 54 cfs (1.5 m3/s; City of Austin, 2013). It is possible that not only Old

Mill Spring but also Eliza Spring could cease to flow during an Extreme Drought under current

(2014) withdrawals without additional curtailments, even if the gates of Barton Springs Pool were

to remain closed. The effect of this circumstance on the Covered Species at Eliza Spring is

unknown, but with no-flow conditions at Old Mill Spring, reproduction appears to cease, food

becomes scarce, and seasonal high temperature in the surface environment causes mortality from

respiratory distress.

33

Recent statewide initiatives that involve the establishment of a 50-year DFC and the associated

amount of MAG have increased the efficacy of the District’s permitting program for managing the

Aquifer under this HCP. In effect, the District was able to incorporate biological resource

conservation into its drought management program and reset the sustainable yield of the Aquifer.

Under these initiatives (House Bill 1763, passed by the 79th Legislature, now reflected in various

sections of Chapter 36 of the Texas Water Code), the District worked with the TWDB to use new

numerical and probabilistic models and scenarios that estimate long-term consequences for Barton

Springs flow under various pumping and climatic scenarios (Hunt et al., 2011). Accordingly, the

District has used the results of groundwater modeling and made associated revisions to the

District’s programs of groundwater management under its continuous incremental/rational planning

approach for adaptive management. These activities are described in Section 4.1.2, Historical

Perspective of Covered Activities. Adaptive management is described in Section 6.4, District HCP

Adaptive Management Process.

At least three groundwater models for the Aquifer (Slade et al., 1985; Scanlon et al., 2001, as

modified by Smith and Hunt, 2004; and Hutchison and Hill, 2010) now exist that can help assure

better management of the Aquifer and protection of the Covered Species. Each model has specific

biases and assumptions and differing means of generating outputs. One may be preferable for

average aquifer conditions, and another may be better suited to analyzing conditions comparable to

the DOR. No one model is ideal for predicting all present and future aquifer conditions and

responses. All three models seem to confirm that, other factors equal, under prolonged severe

drought, one unit of pumpage reduces springflow by that same unit. For example, a regulatory

program measure that reduces the total pumpage during drought by 0.5 cfs (0.014 m3/s) from the

amount that would otherwise be allowed would correspondingly result in a springflow at Barton

Springs that is higher by roughly the same amount (Hunt et al., 2011).

The newest model, developed by the TWDB in support of the MAG determination (Hutchison and

Hill, 2010), takes an approach that is likely to represent actual long-term aquifer performance in a

general sense. The new model is more of a predictive tool that captures the range of uncertainty in

real-world performance than previous models.

The models of Scanlon et al. (2001) and Smith and Hunt (2004) addressed, by calibration to actual

springflow, all known/documented sources of recharge during their calibration periods. However,

there is now evidence of two additional sources of recharge to the Barton Springs segment of the

Aquifer that none of the models explicitly incorporate, both of which have potential implications

for estimating and managing extreme low flow and drought conditions at Barton Springs.

One source is the southern groundwater divide. A recent study has shown surface water from the

Blanco River can flow northward into the Barton Springs segment from the San Antonio segment

during drought conditions (Smith et al., 2012a). The effectiveness of the divide between the two

Edwards Aquifer segments dissipates at low flows, and recharge occurs preferentially to the lower-

elevation Barton Springs segment. Although the Blanco River flowed continuously during the

DOR, increased pumpage in its watershed now has adversely affected its base flow in the

Contributing Zone, and flow might cease during Extreme Droughts. Hunt et al. (2012b) showed

base flow in streams and low springflow decreased during the 40 years preceding the study. Part of

the cause of the decrease could be climate change, over which the District has no control; but a

likely cause is withdrawals in the Contributing Zone, which affect springflow and base flow of

34

creeks. The District also has no control over withdrawals in the Contributing Zone. Another recent

study (Land et al., 2011) has shown the potential for some groundwater in the San Antonio segment

to bypass San Marcos Springs and flow toward Barton Springs under drought conditions. The

induced recharge from this indicated “leaky divide” would tend to flatten the springflow recession

curve at Barton Springs (make springflow over time decrease more slowly) during severe droughts,

even during exceedingly low groundwater levels in the San Antonio segment. However, the

amount of recharge from these sources that would actually occur has not been adequately simulated,

and its potential significance to flow at Barton Springs under severe drought conditions has not

been quantified.

The second source of recharge tends to contradict the assumption that groundwater availability and

springflow will decrease as a result of urbanization and increased impervious cover in the Recharge

and Contributing Zones of the Barton Springs watershed. Investigators have determined that there

is substantial “indirect recharge,” or leakage from utility networks (water mains, wastewater and

storm sewers, and on-site sanitation systems), lawn irrigation return flow, and stormwater

management infiltration devices constructed in the Barton Springs watershed. These indirect

sources of recharge tend to offset the decrease in direct infiltration recharge caused by increased

impervious cover (Wiles and Sharp, 2008; Garcia-Fresca and Sharp, 2005; and Sharp and Garcia-

Fresca, 2004; Sharp, 2010).

Leakage from pressurized water mains, for example, is known to result in utility-scale,

unaccounted-for water losses on the order of 10–30% (Foster et al., 1994). Losses on the order of

12% have been measured in the service area of the COA (Sharp and Garcia-Fresca, 2004).

Irrigation return flow, or overwatering of lawns, parks, and other turfs and pervious landscapes, is

especially common in summer, when the impacts of drought and low flow on the Barton Springs

complex may be severe (Garcia-Fresca and Sharp, 2005). A recent study indicates that total

recharge to the Barton Springs segment in a developed watershed is estimated to be nearly double

that under its pre-urban conditions (Sharp and Garcia-Fresca, 2004). In addition, although it was

estimated that on average only 4% of the total recharge during 1999–2009 was from anthropogenic

recharge sources, the monthly percentage from anthropogenic sources could vary greatly, ranging

from less than 1% to 59% of total recharge (Passarello, 2011). This indirect recharge source has

increased significantly since the DOR calibration period (Smith and Hunt, 2004), when the

watersheds were much less developed than now. To date (2014), this additional recharge has not

been explicitly included in any of the Barton Springs aquifer availability modeling studies.

The quality of indirect recharge is likely to be poorer than native, meteoric Edward's groundwater.

However, there is a considerable amount of dilution and possibly attenuation of pollutant

concentrations in such water by the time it reaches the water table (saturated zone of the Aquifer).

In fact, the studies noted in the previous paragraph suggest that the present water quality in

springflow during low flow may be a result of the combination of native and indirect-recharge

water sources.

In summary, some of the principal considerations related to variation in springflow at Barton

Springs that are important to the Covered Species are:

• Springflow can be highly variable. Extreme low and extreme high daily mean flows differing

by nearly 17-fold have been recorded.

35

• The lowest measured daily flow during the DOR (1950–56) was approximately 10 cfs (0.28

m3/s). The lowest springflow during other 7-year periods not including the DOR years during

the 1913–2013 period of record are considerably higher, typically in the mid-teens.

• There are more than 1,200 operational wells in the Aquifer. The maximum monthly pumpage

was13.6 cfs (0.385 m3/s) in August 2008, and since then, under more recent regulatory

constraints, the monthly pumpage of wells with permits has ranged between 4.3 (0.12 m3/s) and

12.2 cfs (0.345 m3/s), averaging 7.5 cfs (0.21 m3/s).

• In recent years, several individual, severe droughts have produced observable adverse impacts

on the Covered Species’ habitat at all spring outlets, with DO-caused impacts at Old Mill Spring

and Eliza Spring. The habitat typically has not had time to recover from those impacts between

droughts (City of Austin, 2013).

• Groundwater flow models allow for predictions of future aquifer and springflow conditions.

They indicate that pumpage and springflow are related on a 1:1 basis during Extreme Droughts.

A recurrence of DOR conditions with today’s total pumpage would result in springflow

considerably lower than the record low of 10 cfs (0.28 m3/s).

• It is not known whether and to what extent newly ascertained sources of additional recharge to

the Aquifer affect the quality of the habitat of the Covered Species during severe Drought.

3.2.2.2 Ecological Setting

3.2.2.2.1 Overview of Habitat Characteristics and Supported Populations

The four spring outlets of Barton Springs and their proximal subterranean areas are believed to

form the primary habitats where the Covered Species are concentrated. Secondary habitat, at

least for the Barton Springs salamander, evidently exists in the subsurface throughout the

Aquifer, although the size and distribution of these populations remote from the spring complex

are very poorly known. The better documented habitats and other supported flora and fauna at

the outlets are described in substantial detail in Appendix C.

The salamander populations in the Aquifer and in its discharge at Barton Springs experience

relatively stable aquatic environmental conditions in their habitat compared to typical lotic (open

flowing stream) ecosystems. Changes in environmental parameters9 are typically gradual and

within fairly narrow ranges, with the extremes generally associated with floods and prolonged

droughts. These conditions consist of perennially flowing spring water that is usually clear, has

a neutral pH (~7) (neither acidic nor basic), and maintains cool annual temperatures of ~21 °C

(~70 °F) (Service, 2005). As is typical of large, groundwater-dominated springflows, Barton

Springs’s flows on the falling limb of the recession curve (period of decreasing flow after an

increase in flow associated with a storm) generally have a narrow temperature range

(stenothermal). During wet periods, springflow on the rising limb of the recession curve (period

of increasing flow after a storm) may be more affected by the prevailing ambient temperature of

9 A parameter in an environmental context means a characteristic, feature, or measureable factor that can help define a

system. For example, "water quality parameter" commonly refers to a water property or chemical constituent.

36

local surface runoff that rapidly recharges the Aquifer immediately following storms (Mahler

and Bourgeais, 2013). Clean springflow with a relatively constant, cool temperature is essential

to maintaining well-oxygenated water necessary for salamander respiration and survival

(Service, 2013b; Service, 2005). DO concentrations differ somewhat among the spring outlets

(City of Austin, 2013). At the larger outlets of Barton Springs, DO concentrations range

between 4 and 7 mg/L, average about 6 mg/L (Service, 2005), and are directly related to

springflow. During low flow and associated low DO conditions, the DO concentration of water

after it issues from an outlet will tend to increase, other factors equal, especially in spring run

environments owing to re-aeration of the water with low DO concentration. However, the

reduced DO solubility of higher temperature water during summer months, likely exacerbated by

pooled water environments, may limit such DO concentration increases seasonally and/or from

time to time (City of Austin, 2013; Smith-Salgado, 2011).

The USGS has documented an increasing amount of nutrients and organic matter over time in

the recharge streams of the Aquifer, which may have consequent DO demand. But as of 2014, a

relationship has not been established between DO concentration in recharge water and reduced

DO concentration at the primary outlet within Main Springs during drought flows (Mahler et al.,

2011). However, the COA has recently shown a statistically significant overall downward trend

in DO concentrations averaged over the range of Barton Springs flow, from all individual outlets,

from 5.7 mg/L in 2000 to no more than 4.5 mg/L in 2014 (Porras, 2014). This general trend

likely relates to additional pollutant discharges in the recharge water, although some part of that

trend may also relate to deeper and more prolonged droughts during 2000–2014. Sustained low

DO concentrations occur primarily during periods of moderately low springflow (Herrington and

Hiers, 2010; Turner, 2009; Service 2005). A recent USGS study of the water chemistry

associated with springflow extremes over the last several drought cycles (Mahler and Bourgeais,

2013) also shows that DO concentrations at the primary outlet of Main Springs during the period

of that study decreased on occasion during the more transient high flows of some storms. The

decreases presumably arise from oxygen-demanding materials in the “first flushes” of runoff,

and/or also by seasonally warmer temperatures of recharging surface water. Other outlets may

reasonably be inferred to experience similar effects in the future, if not now.

The District’s Covered Activities potentially affect the entire populations of both Covered

Species, at least during severe droughts, in both surface habitats at the outlets and at subterranean

habitats throughout the Aquifer. (This is unlike the COA’s covered activities, which only affect

the surface populations from time to time and only in the vicinity of the Barton Springs outlets.)

Both of the Covered Species are considered to each have two cohorts (used here to denote sets of

individual members of a population of the same species) for purposes of estimating population

sizes in this HCP: a near-field one in the vicinity of the Barton Springs complex; and another,

far-field one at locations in the Aquifer remote from the complex. Different methods for

establishing approximate abundances are used for each of these population cohorts, and for each

of the Covered Species.

Near-field Cohorts Proximal to the Barton Springs Complex

Owing to the factors described above, as well as to the natural drought- and withdrawal-induced

variations in springflow, habitat conditions in the vicinity of Barton Springs likely will support

variable numbers of individual salamanders from time to time, even for the same spring outlets

37

and for similar springflows. This is reflected in the variability of the counts of Covered Species

made by biologists from the COA, who performed approximately monthly counting surveys at

all four Barton Springs outlets between 2004 and 2014, summarized in Table 3-2. These surveys

provide the most consistently collected set of long-term count data for these sites.

Table 3-2: Population statistics of the Covered Species based on surface survey counts.

These estimates are based on counts using a consistent methodology and do not include that portion of the

population that is at that surface location but is inaccessible for counting. The population size varies with time but

for purposes of calculating take in the COA's (Barton Springs Pool) HCP, it is inferred and stipulated to be the sum

of mean abundance plus one standard deviation. Source: City of Austin (2013).

Indicated

Abundance

(Mean of Counts) SD

Inferred

Population

Range of

Counts

Barton Springs

salamander:

Main Springs 74 86 160 5-447

Eliza Spring 349 275 624 3-1234

Old Mill Spring 15 22 37 0-73

Upper Barton Spring 6 12 18 0-100

Total Indicated

Population

839

Austin blind

salamander:

Main Springs 0.4 0.9 2 0-5

Eliza Spring 1.1 2.2 4 0-12

Old Mill Spring 15 22 37 0-73

Upper Barton Spring 0 0 0 0

Total Indicated

Population

43

As shown in this table, COA biologists have previously used a mean-plus-one-standard-deviation

(SD) metric, based on organism abundance density10 from the recurring observations of each

Covered Species at the spring outlets, to infer the surface habitat-dwelling population of

individual salamanders affected by the COA's covered activities—that is, the COA's take.

However, these counts and analyses do not take into account in a rigorous fashion those portions

of the salamander populations that at least occasionally occur at the surface but at the time of

counting are subterranean and not accessible for counting. Taken together, the aggregate of the

two portions of the populations that are and aren’t accessible for counting is termed the

10 Salamander counts vary between sampling events and with environmental conditions. The mean-plus-one-SD metric

represents a consistent way to estimate the actual population that would be accessible for counting between sampling

events. It is based on the average of and variation in sample salamander counts.

38

“superpopulation”. COA biologists since 2014 have been employing, in lieu of simple counts

and statistics, a capture-mark/release-recapture (CMR) approach to making quarterly census

surveys for the Covered Species at the individual spring outlets and are now using a more

sophisticated estimation model algorithm to calculate both the populations and the

superpopulations (COA, 2017a).

To date, the superpopulation abundance only of the Barton Springs salamander and only at Eliza

Spring has been confidently estimated using CMR. The other outlets and the other Covered

Species have not had sufficient amounts of recapture to use CMR, and because of their relatively

low counts and re-capture rates of marked individuals, these other outlets are not expected to

produce useful CMR superpopulation estimates (COA, 2017b). But the average abundance of

Barton Springs salamander at Eliza is modeled by CMR relatively confidently to be 855

organisms, with a calculated effective capture probability at this outlet for this time period of

0.19. This result connotes that a large proportion of this population, roughly four-fifths, was

frequently unavailable for capture during this three-plus year period, so it is likely that

individuals able to be counted at the surface at any one time are only a rather small fraction of

the total population that inhabits the spring, viz., only about one-fifth at Eliza. The study period

here was relatively short, and also one that corresponded only to non-drought conditions, and the

effective capture probability even at this outlet might well be different during a longer time

period that also included sustained low-flow conditions during drought. Further, even for a

longer period of time that includes drought and non-drought, the capture probabilities at the other

outlets may be substantially different than that at Eliza Spring, because of differences in

hydrology, surface-subsurface connectivity, and substrate characteristics. So the District did not

apply the CMR-based capture probability at Eliza, i.e., 0.19, to other outlets because it would

introduce additional uncertainties and unknowns. COA notes the many assumptions and

attendant issues associated with comparing CMR-based data among spring sites and for different

time periods, but on balance it also observes it is better to apply some CMR data-based factor to

counts for estimating superpopulations for different sites and time periods than to rely upon

uncorrected counts alone (COA, 2017b).

Accordingly, for purposes of this HCP, the District calculated a “correction factor” based on the

ratio of (a) the CMR-established best-estimate population at Eliza Spring (i.e., 855 individuals)

to (b) the average of counts at Eliza over the longer time period that included both drought and

non-drought conditions (i.e., 349 individuals in Table 3-2). It then applied that same correction

factor to the longer-term average counts of Barton Springs salamander at the other outlets to

estimate the populations at all outlets:

Eliza Spring: 855/349) x 349 = 855 (see above)

Main Springs: (855/349) x 74 = 181

Old Mill Spring: (855/349) x 15 = 37

Upper Barton Spring: (855/349) x 6 = 15

Total, All Outlets: 1088

At best, these are just a first-order approximation of the superpopulations of this epigean species

at and near the outlets. Nevertheless, for purposes of this HCP the District is stipulating that

these are the populations of the Barton Springs salamander in the near-field cohort to be

included in the total population for estimating take. While not anticipated, should continuing

39

investigations produce new information in the future that suggests the total estimated population

or the populations at individual outlets are significantly different than stipulated here, the District

would then re-assess the amount of take based on such new population information and execute

other actions described in Section 7.3, Unforeseen Circumstances.

The superpopulation of the largely subterranean Austin blind salamander is unreliably estimated

by any counting-based technique. Simply put, even for the near-field cohort, it is impossible to

accurately determine the population size of a subterranean salamander species on the basis of

number of individuals counted or inferred in surface habitat. So there is little confidence that the

population numbers for the Austin blind salamander shown in Table 3-2, which are based only

on such observations, are accurate, even for the population cohort in the region of the outlets.

The small number counts for the Austin blind salamander shown in this table are almost certainly

more a function of its inaccessible subterranean habitat than its actual population size. And it

militates against the use of CMR, as used for the Barton Springs salamander, to estimate its

superpopulation.

Because the surveyed counts for this population reflect only the surface population component of

this subterranean species, which occurs at the surface only incidentally, the District has

developed an alternative estimate that it considers more realistic for this population cohort. In

absence of available data, some rational assumptions are required in making this estimate for

such a cryptic species; the extent to which these assumptions are approximately correct is not

known. Key elements and assumptions used by the District in making the calculation include:

A. a Subterranean Density (0.0025 individuals per square foot of Inhabitable Voids) that is

different than, and nominally one-half of, the surface density for the Austin blind

salamander at the outlets (0.005 individuals per square foot) that has been established by

the City of Austin biologists (City of Austin, 2013, Table 11);

B. a subterranean Potential Habitat Region for the Austin blind salamander that coincides

with the entire Service-designated 120 acres (5.2 million square feet; 48.6 hectares) of

Critical Habitat (Section 5.1.2.2, Austin Blind Salamander)11;

C. an area of Active Habitat, referring to the circumscribed portion of the potential habitat

area that is in fact inhabited under conditions prevailing at a given time, is nominally one-

half of the Critical Habitat Area, although the actual geographic area of the active habitat

in the x-y dimensions will likely vary with time and especially with groundwater levels in

the Aquifer (the proportion of Active Habitat will likely have an inverse relationship with

the size of the potential habitat area);

D. the portion of the Active Habitat area in x-y dimensions that comprises Inhabitable

Voids at the prevailing Aquifer water level is 15% of the area in map view,

corresponding to connected secondary porosity of the Aquifer (with the remainder being

solid rock matrix or voids that are too small and/or inaccessible to be inhabitable); and

E. the large majority of the subterranean salamander population at any one time will be near

the water table in the inhabited area, where some DO reaeration with the atmosphere

occurs and thereby produces larger and more stable DO concentrations, such that the

11 The Critical Habitat Area designated by the Service (2012) is not, strictly speaking, intended to delimit the area in

which the Austin blind salamander may or may not be found. However, given its small size that closely circumscribes

the individual outlets, for purposes of this HCP it is considered the area that could be potential habitat for this species.

40

salamander is not considered to be additionally distributed in the z-dimension and

therefore no x-y layers stacked in the z-dimension exist or need to be included.

Using these parameters, calculation yields:

Number of ABS Individuals = A x B x C x D x E

= (0.0025 individuals presumed/inhabited sf)

x (5,200,000 sf total area)

x (0.50 active area/total area in plan view)

x (0.15 inhabitable void area/active area in map view)

x (1.0 vertical layers of habitat)

= 980 individuals ≈ Population of 1000.

Accordingly, in the absence of relevant data or countervailing analyses, for purposes of this HCP

the District is stipulating that the subterranean Austin blind salamander population of this

near-field cohort is 1000, rather than the surface-only population indicated in Table 3-2 for the

Austin blind salamander (shown as 43 individuals). The stipulated subterranean population of

1000 relates to the number of individuals in the vicinity of the Barton Springs complex that

might potentially be affected by the groundwater flowing through the Aquifer. (In contrast, the

much smaller surface-only population relates to the number of individuals of this subterranean

species that might be affected by the surface activities near the outlets that are covered by the

City of Austin’s HCP.)

Further, the surface observation-based statistics by spring outlet for the Austin blind salamander

are not considered indicative of the relative spatial distribution of their population within their

subterranean active habitat. It is possible that such distribution throughout the Aquifer during all

flow conditions is not closely related to springflow conditions at the various outlets. But for

purposes of the take assessment in this HCP, the proportional population distribution among the

outlets is assumed to be related to the flow regimes (and therefore the quantities and average

flow velocities) of water discharging at the individual outlets, and that this relation is likely to

become more pronounced as combined spring flows decrease. That is, other factors equal,

during low-flow conditions salamanders will tend to congregate in the subsurface where the

groundwater flows are larger. For purposes of assessing take in this HCP, the District is

stipulating that the outlet-specific populations of the Austin blind salamander are indexed

to Stage III Critical Drought flows at the individual outlets, specifically those at a combined

springflow of 20 cfs (0.57 m3/s). Using COA measurements and analyses (City of Austin,

unpublished data, 2014) for the flows at individual outlets yields the proportionate outlet-specific

populations for the Austin blind salamander in Table 3-3. These initial outlet populations would

be exposed to DO concentrations associated with that particular outlet, although such exposure

would be largely in the subsurface and is likely to be an ever-changing mix with time.

The distribution of the Covered Species and the DO concentrations differ among the spring outlets,

so population estimates for this cohort are provided above by outlet. However, unlike the COA

ITP, in which its covered activities differ among the spring outlets and even within various parts of

each of the outlet habitats, the District’s management of groundwater withdrawals cannot be parsed

among the spring outlets. Nevertheless, the amount of take that results from the District’s Covered

41

Activities is partitioned among the individual spring outlets on the basis of their specific DO-

concentration relationship with combined springflow. But simply put, the District’s Covered

Activities cannot “target” where take occurs and doesn’t occur among the outlets, although it is

readily apparent that the effects will be disproportionate among the outlets, and take estimates and

impact assessment should account for those differences.

Table 3-3: Estimated population distribution of Austin blind salamander at each outlet.

Spring Outlet Stipulated Population

Main Springs 877

Eliza Spring 111

Old Mill Spring 12

Upper Barton

Spring

0

Total 1000

In summary, the inferred and stipulated abundances of both Covered Species near Barton Springs

are quite small. The overall conclusion is that these populations are subject to stressful changes

in near-field habitat conditions on a recurring basis, and therefore concern for their continued

existence, absent extraordinary attention, may be well-founded.

Far-field Cohorts Remote from Barton Springs Complex

Other than the very few locations reported as habitat miles away from Barton Springs, little is

known about the characteristics of this relatively recently discovered cohort. It may or may not

be relevant that unlike the Barton Springs salamander, no occurrences of the Austin blind

salamander have been reported at these remote locations to date. Further, statistically useful data

exists only for one far-field location for the Barton Springs salamander, at Blowing Sink Cave.

But it is sparse, and there is no statistically valid way to estimate the overall size of the

population(s) in the far-field cohort using only the Blowing Sink count data. Their distribution

in the subsurface, e.g., whether individuals are more or less uniformly distributed throughout the

Aquifer or their occurrence is restricted in some way, is not currently known. During the term of

the ITP, it is anticipated that more information about these cohort(s) will be reported and may be

incorporated into the HCP and ITP (see Section 7.2.2.1 for the related Changed Circumstance).

The City of Austin has recently documented seven springs/seeps that are newly discovered

locations of the Barton Springs salamander (City of Austin, 2017a). Four of these seven

springs/seeps issue from the Glen Rose formation and are in the Contributing Zone outside the

ITP Area. But three of the seven are located within the ITP Area, and join a number of other

locations in the Aquifer that are known, documented habitat for the Barton Springs salamander,

as described in Section 5.1.2.1, Species Distribution, Barton Springs Salamander. It is

significant that all these habitat locations are on or near confirmed secondary or primary

preferential flow routes (refer to Figure 3-2, in Section 3.1.2.2, Groundwater Flow Conditions),

which suggests that the distribution of this cohort may tend to be more likely concentrated along

the known flow paths.

42

Blowing Sink Cave is the only location of known subterranean Covered Species’ habitat within

the Aquifer that is accessible by people for counting individual organisms. To date, the COA has

conducted seven counting campaigns at this location for Barton Springs salamander, with counts

ranging from 1 to 6, a mean near 3, and an average approximate density of 0.070

salamanders/square meter, or 0.0065 salamanders/square foot (City of Austin, 2017b). As noted

above, it would be surprising to find that this density is representative of the entire far-field

cohort; it seems more likely that the average density would be appreciably less for those larger

subterranean areas that do not have direct connections to the surface.

As with the Austin blind salamander in the near-field cohort, the absence of representative data

requires the District to make some rational assumptions in estimating the size of this more

cryptic population cohort of the Barton Springs salamander (BSS) for the HCP. It is not

currently determinable to what extent these assumptions are approximately correct. Key

elements and assumptions used by the District in the calculation include:

A. an average Subterranean Density of 0.007 individuals per square meter, or 0.00065

individuals per square foot, of Inhabitable Voids, that is on average nominally an

order of magnitude smaller than the calculated density of the Barton Springs salamander

within the near-surface Blowing Sink Cave, as described above;

B. a subterranean Potential Habitat Region for this cohort of the Barton Springs

salamander that corresponds to the total area of the primary and secondary

preferential flow paths through the Aquifer (see Section 3.1.2.2, Groundwater Flow

Conditions, Figure 3-2), beginning at the boundary between unsaturated and saturated

zones during moderate drought, as mapped by the District and approximated by the

boundary between the District’s Western Edwards and Eastern Edwards Management

Zones and including both unconfined and confined flows to Barton Springs; this includes

an aggregate linear distance of about 75 miles (396,000 feet), as estimated by District

hydrogeologists, and an average effective flow-zone width nominally of 1000 feet

(although indeterminate, it will tend to be considerably more diffuse in the upper parts of

the flow path and possibly more restricted in the lower parts of the flow path), which

comprises a Potential Habitat Region of about 396 million square feet (3685 hectares)

for this cohort of the Barton Springs salamander;

C. the portion of the Potential Habitat Region that is Active Habitat, i.e., the circumscribed

area that is inhabitable and inhabited under conditions prevailing at a given time, is

nominally an average 10% of the Potential Habitat, although the actual geographic

areas of active habitat in the x-y dimensions would vary with time and especially with

groundwater levels in the Aquifer that control the preferential flow paths, and the actual

proportions of Active habitat would likely differ between upper and lower parts of the

flow routes (in addition, the proportion of active habitat area would likely have an inverse

relationship with the actual size of the potential habitat);

D. the portion of the Active Habitat area in x-y dimensions that comprises Inhabitable

Voids at the prevailing Aquifer water level is stipulated to be 15% of the Active Habitat

area in map view, corresponding to connected secondary porosity of the Aquifer (with the

remainder being solid rock matrix or voids that are too small and/or inaccessible to be

inhabitable); and

43

E. the large majority of the subterranean salamander population at any one time will be near

the water table in the Inhabitable Voids, where some DO reaeration with the atmosphere

occurs and where less of the groundwater is mixed with deeper, DO-depleted water from

the saline zone; this produces larger and more stable DO concentrations in the

groundwater of the active habitat, such that the salamander is not considered to be

additionally distributed in the z-dimension and no x-y layers stacked in the z-dimension

need to included.

Using these assumptions and parameters, calculation yields:

Number of BSS Individuals = A x B x C x D x E

= (0.00065 ind presumed/inhabited sf)

x (396,000,000 sf total area)

x (0.10 active area/total area in plan view)

x (0.15 inhabited area/active area in map view)

x (1.0 vertical layers of habitat)

= 3861 individuals ≈ Population of 3900.

For purposes of this HCP and in the absence of relevant data or countervailing analyses, the

District is stipulating that the population of the far-field cohort of the Barton Springs

salamander is 3900.

The Austin blind salamander has not been reported in Blowing Sink Cave or at any other far-

field location. Even though this Covered Species is morphologically similar to the Texas blind

salamander that occurs in the subterranean portions of the southern (San Antonio) segment of the

Edwards Aquifer, the District has no basis for estimating the size of this cohort. It only suspects

that it may be present at some far-field subterranean locations in the Aquifer, especially those

closer to the near-field cohort. So for now, the District is simply stipulating that the

population of the far-field cohort of the Austin blind salamander is greater than zero, and

nominally 5% of its near-field cohort, or 50 individuals.

Stipulated Abundance of the Covered Species and Related Take Considerations

For purposes of this HCP and in summary, the populations of both cohorts for each of the

Covered Species, as described above, have been stipulated by the District as follows:

Barton Springs salamander: 1088 + 3900 = 4988

Austin blind salamander: 1000 + 50 = 1050

Take may occur for similar reasons in both cohorts and in both Covered Species, and take

estimates are based on these stipulated total abundance amounts. However, for either species,

the information available does not afford an unequivocal estimate of the sizes or spatial

distribution at any given time of these populations, especially the near-field Austin blind

salamander and the far-field Barton Springs salamander. Further, the number of individuals in

these generally small populations likely varies considerably with environmental conditions,

presumptively indicating their sensitivity to habitat conditions (see, for example, the ranges

44

shown in Table 3-2 above). And as noted above, while the populations and amounts of take for

either Covered Species at any given time will differ among the outlets, the interconnected

hydrogeology of the Aquifer does not allow the District regulations on groundwater withdrawals

to be outlet habitat-specific.

3.2.2.2.2 Water Chemistry and Springflow Relationships

Water quantity, water chemistry, and quality of water in the Aquifer and in springflows are

interrelated. High flow, especially stormwater runoff, generally is relatively poor quality with

respect to many water quality parameters, including suspended solids, nutrients, bacterial loadings,

and oxygen-demanding material. But runoff events also are transient. Such transient stormwater

has low (below water quality standards for surface water) DO concentrations (Mahler and

Bourgeais, 2013) and relatively small TDS concentrations (salinity). Low DO concentration is

likely caused by relatively high oxygen demand and/or induced release of water from aquifer

storage that is depleted in oxygen, as well as variable, seasonal water temperature that affects DO

solubility, with colder water allowing higher DO concentrations than warmer water. Average flow

and especially typical drought flow tend to be generally higher in quality (that is, has smaller

pollutant loads than those in stormflow), and lower water levels and smaller springflows typically

have water of more uniform temperature that reflects the Aquifer conditions, As drought is

prolonged and springflow decreases over an extended period), DO concentration tends to decrease

and salinity tends to increase over a somewhat restricted observed range (Herrington and Hiers,

2010). These phenomena during severe drought, when much less or no oxygenated surface

recharge to the Aquifer is occurring, appear to be related to the discharged amounts of older, more

saline water from confined parts of the Aquifer, including possibly the hydrologically connected

Saline Zone or underlying confined Trinity Aquifer, all of which have much lower DO

concentration (Mahler and Bourgeais, 2013; Lazo-Herencia et al., 2011; Johns, 2006). In addition,

these studies suggest that the relative contributions to flow at the individual spring outlets, from

various flow routes with different DO concentrations and possibly different salinities, could vary

with total springflow (Hauwert, 2004) and also affect the relationships observed. The natural

introduction of water with relatively low DO concentration and relatively high salinity, regardless

of other factors that might be reflected in the water chemistry and quality, is caused in part by the

Covered Activities. DO and salinity are the two springflow-related water chemistry parameters that

are believed to be of primary potential importance in determining the amount of take of the Covered

Species in the spring habitats by the District’s Covered Activities. For these parameters, their

characteristics as measured in springflows are presumed to be on average generally similar to those

in the groundwater throughout the Aquifer at that time, although localized differences may exist. In

particular, groundwater in the unconfined portion of the Aquifer has significantly higher DO

concentrations than groundwater in the confined portion of the Aquifer (Lazo-Herencia et al.,

2011).

Dissolved Oxygen and Springflow

The concentration of DO has been known for some time to correlate directly with springflow at

Barton Springs (City of Austin, 2013; Herrington and Hiers, 2010; City of Austin, 1998). DO tends

to be at relatively high concentrations during periods of high recharge when a large volume of well-

oxygenated surface water that is not stormwater enters the aquifer. DO levels are at their lowest

when recharge is minimal or nonexistent and springflow is low (Herrington and Hiers, 2010; City

of Austin, 1997). (During such extended drought periods, the effects of temperature on DO

45

concentration caused by temperature-related solubility differences are more muted, because the

temperature of the water in the Aquifer and discharging as non-stormwater springflow tends to be

more uniform.) Extended or frequent periods of low flow, therefore, can be detrimental to the

development, reproduction, and even survival of the Barton Springs salamander. However Norris

et al. (1963), while confirming the adverse effects of low DO concentration, also notes that some

salamander species physiologically accommodate low DO concentration; the biochemical basis for

such accommodation has been more recently investigated by Issartel et al. (2009). Although the

Barton Springs salamander persisted through the drought of the 1950s and likely earlier, even more

severe and prolonged droughts (Cleaveland, 2006; Cleaveland et al., 2011), its population may have

been larger earlier in its history, perhaps even not unique to Barton Springs. But its population size

may have been adversely, possibly permanently, affected by prolonged low flows at Barton

Springs, particularly if DO concentrations were proportionally low. Depressed DO concentrations

also may compound the effects of other stresses on salamander survival, such as increased pollutant

loading during drought and low-flow conditions. A key adaptive objective of this HCP is to

increase the understanding of the relationships between springflow and DO concentration in the

Barton Springs complex and further afield in the Aquifer, and to develop over time an enhanced

capability to minimize or avoid anthropogenic lowering of DO concentration through groundwater

management during low-flow conditions.

Science staffs at the COA, TWDB, USGS, and BSEACD have collaborated for several years to

collect, compile, and analyze water quantity and quality data from the Barton Springs complex.

These collaborations have included studying the correlation of springflow, DO concentration, and

other relationships. There is considerable agreement that strong correlations exist between

springflow and DO concentration, within the ranges of springflow for which data have been

collected. There is some variability in the data-collection instrumentation, methods of collection

and analysis, and frequency and areal extent of data collected by the different entities, all of which

affects accuracy, precision, and/or usefulness of the data. Such limitations in making inferences in

this HCP are noted in appropriate places. Further, the relationships differ among the individual

spring outlets. Appendix D summarizes the outcomes of several representative investigations of

these relationships conducted by the COA Watershed Protection Department, describing the results

of these studies in detail and also presenting summary statistical analyses of the data.

Reliably measuring in-situ DO concentration of groundwater is a well-known challenge. In one

such recent study of the Aquifer (Lazo-Herencia et al., 2011), median DO concentration of native

groundwater in the Recharge Zone was 6.4 mg/L, and median DO concentration in the Confined

Zone was substantially lower, 2.0 mg/L. These results support the notion that more water from the

Confined Zone adjacent (both laterally and vertically) to the spring outlets discharges from the

outlets at low water levels, resulting in a decrease in DO concentration with decreasing springflow.

A more recent USGS study (Mahler and Bourgeais, 2013) of the Aquifer and flow at the primary

outlet of Main Springs over a 6-year period with high and low groundwater levels and springflow

found DO concentrations fluctuating by a factor of two. In addition, the study data show DO

concentration generally related inversely to springflow temperature and directly to springflow; and

Mahler and Bourgeais (2013) note that both relationships are likely to be strengthened by climate

change. The lowest DO concentration observed by those investigators was 4.0 mg/L, consistent

with a water-source model of mixed water types in approximately equal proportions. Main Springs

consistently has higher DO concentrations than the other outlets and considerably lower DO

concentrations have been measured at the other outlets than at Main Springs.

46

A salient aspect of the data and analyses in Appendix D is that relatively few paired, combined

springflow and DO data exist in the springflow domain below 20 cfs (0.57 m3/s), which is the more

critical region for assessing significant take. Figure 3-7 shows the range in predictions of DO

concentration for the aggregated sub-outlets at Main Springs that can be expected from various

regression models12, which were developed by COA staff under various boundary conditions in the

zone of flow less than 20 cfs.

Regression models for individual spring outlets, such as those shown in the figures in Appendix D,

do not have well-established, reliable predictors of DO concentration with combined springflow in

the zone of flow less than 20 cfs, owing to sparse or non-existent data. For example, from 1978 to

the present time, the minimum DO concentration observed by the USGS at the primary outlet of

Main Springs is approximately 4 mg/L, when the combined springflow was reported to be 13 cfs

(0.37 m3/s) in August 2009 (the previously noted measurement difficulties notwithstanding). The

COA regression model (Saturation Growth-Rate, Figure 3-7) for Main Springs indicates that the

predicted DO concentration would be 3.4 mg/L at a discharge of 13 cfs, which is lower than the

actual observed value at that discharge. (The USGS collected its data at just one outlet, the primary

outlet of Main Springs, but the regression relationships were developed by the COA for the

aggregated sub-outlets of Main Springs). The logarithmic function used in this and some of the

other models predicts that DO concentrations would decrease to 0 mg/L at or above a discharge of 0

cfs. Although this outcome is conceivable, the prediction is a product of the mathematics, not DO

and springflow data at very low values, which are unavailable. Other models predict different but

also conceivable outcomes, with DO concentration decreasing only to about 4 mg/L. Those

outcomes appear to be more in keeping with results established at high flows where there are data

to support the mathematical relationships. USGS staff, using a multivariate model, calculated that

the DO concentration at the primary outlet of Main Springs would be 3.99 mg/L under no-flow

conditions (Mahler and Bourgeais, 2013). The same caveats regarding lack of actual DO-

concentration data at such low flows apply to these results as well.

In assessing the usefulness of the existing data and analyses for evaluating adverse effects and

impacts of take on the Covered Species, their limitations and uncertainties should be considered.

Some of the more important of these limitations follow.

In the laboratory study of salamander response to the stressor depressed DO concentration (Poteet

and Woods, 2007), which is presented in Section 5.2.1, Experimental Assessment of Salamander

Responses to Changes in Water Chemistry Related to Springflow, there were only 35 DO

concentration observations less than 4.5 mg/L for Main Springs in the available USGS dataset that

was used to assess the usefulness of the laboratory results. Woods et al. (2010) extended that

assessment with an ecological hazard assessment and found no statistically significant relationship

between low flow and associated DO concentration for this limited USGS data set. Even less

information for Eliza Spring and Old Mill precluded similar evaluations for those sites. The

relationship between springflow and DO concentration for flows less than 20 cfs is important to a

quantitative assessment of take, but that relationship is not known with certainty.

12 A regression model in this context is an equation that relates DO concentration (dependent variable) to springflow

(independent variable). Several different techniques are available to develop regression models.

47

Figure 3-7: Various regression models representing relationships between springflow of the

aggregated sub-outlets of Main Springs and dissolved oxygen concentration. These regression models are based on flow data that do not extend into flows less than about 20 cfs. Source: Turner

(2007).

Nevertheless, there is clear evidence of depressed DO concentration with smaller springflows

observed in the overall datasets at specific spring outlets. In particular, DO concentration at Old

Mill Spring is known to plunge when the combined Barton Springs flow declines toward 20 cfs.

Sustainable yield simulations done by the District in 2004 indicate that under 1950s DOR

conditions and large withdrawals, water from the Saline Zone has a greater potential to move into

the freshwater part of the Aquifer (Smith and Hunt, 2004). Water in the Saline Zone tends to be

more depleted in DO than water in the unconfined and freshwater parts of the Aquifer.

Not all of the data available for the Barton Springs complex have been collected with the same

instrumentation, over the same time period and frequency, or compiled and analyzed using the same

protocols. Most of the DO data shown in Figure 3-7 were collected from the various spring orifices

by the COA, using grab-samples from both automatic and manual monitor stations. If different

data sources were to be used and compared to the results described, the outcomes in the zone of

extreme low flow may appear significantly different. In particular, the datasondes yield lots of data

related to all flow conditions, but there is no data available to characterize DO during extreme low

flows, below 14 cfs monthly average flow. And although useful for some purposes, data from high

(including storm) flows, which can have low DO (Mahler and Bourgeais, 2013), confounds the

analysis and prediction of DO concentration during extremely low base flow. And extremely low

flow is the most import to the Covered Species in assessing take.

Further, at very low flows, the reliability of individual springflow measurements is impaired

because of magnified effects of factors not related to springflow—factors such as differences

among measurement personnel, altered or unstable cross-sections, and changes in backwater effects

48

from slight rises and falls in Lady Bird Lake elevation during discharge measurements. Hunt et al.

(2012a) showed that flow measurements can vary by as much as 30% during low flow. So there is

a corresponding uncertainty in the correlation among flows at different times and in the correlation

of flow to DO concentration.

There is also uncertainty, if the DOR were to recur, as to how low the combined springflow at the

Barton Springs complex might decline now. The current drought management program of the

District and this HCP is designed to provide a base springflow during a DOR recurrence (refer to

Section 6.2.1.8, Addressing Quantitatively the Established Desired Future Conditions, for the

desired outcome of proposed HCP measures). This regulatory program is indexed to authorized

groundwater use, but actual groundwater use in aggregate historically has tended to be less than the

prevailing curtailed authorized use (reflected in Figure 3-9), allowing for higher-than-predicted

springflow. Further, the regression models described in this section are limited by the lack of data

under extreme low-flow conditions as well as variations in source data and other factors noted. No

known scientific studies integrate other independent but related factors into predictions of DO

concentration under extreme low-flow conditions. Nevertheless, given the considerable uncertainty

that must be addressed in such situations, the regression models provide understanding and help

frame and prioritize management alternatives on the basis of the possible consequences of various

actions (or no action).

An analysis was done of DO concentration and several other water quality parameters at Barton

Springs over a 25-year period, adjusting for variations in springflow (Turner, 2000). The analysis

of water quality records, collected by the COA from 1975 to 1999, indicated statistically significant

changes in DO concentration over the 25-year period, possibly related to watershed urbanization.

DO concentration in both high and low springflows decreased over time. The median DO

concentration decreased by about 1 mg/L over the 25 years 1975–99, from 6.4–6.8 mg/L in 1975 to

5.45–5.7 mg/L in 1999, a decrease of about 15%. Sampling has been more frequent recently,

leading to a higher probability of observing extreme events. Therefore it is possible that the

observed change is a sampling artifact (Turner, 2000). Enhanced nonpoint-source pollution

controls in the Barton Springs watershed have been initiated by the COA, Travis County, and

several municipalities to arrest or slow this decline, but recent statistical analyses by the COA

suggest that the temporal trend in decreasing overall DO concentration is continuing, and the

median is now less than 4.5 mg/L (Porras, 2014). A long-term change in DO concentration of

greater than 1.0 mg/L is likely meaningful in any isolated aquatic habitat. Trends in other water

quality parameters such as nutrients and total suspended solids in springflow were not as clear or

notable (Turner, 2000). A more recent USGS report on water quality trends in the Barton Springs

recharge streams and at Barton Springs (Mahler et al., 2011) indicated that low flow during dry

periods did not show water quality impacts by suspended solids, nutrients, and bacteria at Barton

Springs; but during wet periods and stormflows, those parameters in streams, the Aquifer,

streamflow showed significant increases associated with watershed development.

Salinity and Springflow

The specific conductance of springflow, a measure of the concentration of TDS (salinity) in the

water issuing from the Aquifer, as well as individual ion concentrations, have been known for some

time to increase as springflow decreases (for example, Slade et al., 1986; Senger and Kreitler,

1984). The general relationship is shown in Figure 3-8, depicting paired specific conductance and

springflow data collected by the COA over a 7-year period that includes very high and very low

49

springflow (Herrington and Hiers, 2010). Specific conductance varies within a fairly narrow range.

The difference in specific conductance of the average flow and specific conductance of the lowest

flows in this dataset is about 75 μSiemens/centimeter. This corresponds to a variation in TDS of

less than 50 mg/L. That amount of overall salinity variation for all flows is not much more than the

salinity variation observed in all measurements of a given flow. Even at the lowest flows, the

highest TDS concentrations of springflows reflected by these data are about 475 mg/L, less than

one-half the concentration considered freshwater (less than 1,000 mg/L TDS) and supportive of

aquatic life. However, TDS or specific conductance data for extreme low flow, such as would exist

during a recurrence of the DOR, are not available, so the actual salinity of such DOR flow is

unknown.

Researchers have postulated that the increase in salinity under low-flow conditions is caused by a

greater proportion of springflow being contributed by water from the Saline Zone (Slade et al.

1986; Johns 2006). Low water levels in the freshwater zone of the Aquifer associated with low-

flow conditions can result in an increase in pressure from the Saline Zone toward the freshwater

zone of the Aquifer. Similarly, water from the underlying Trinity Aquifer could possibly migrate

upward along faults that relate to the spring outlets, but there is no evidence of such

interformational flows elsewhere in the District (Wong et al, 2014; Smith and Hunt., 2011). So the

Trinity Aquifer seems a less likely source of brackish/saline water to the outlets. On the basis of

hydrochemical data analysis and use of mixing models, Hauwert et al., (2004) suggested that about

3% of the springflow at Old Mill and 0.5% at Eliza and Main Springs might be derived from such

sources during low-flow (17cfs; 0.48 m3/s) conditions. This is consistent with the observed small

but statistically significant differences in salinity among the various spring outlets. Not all spring

outlets have such salinity variation, presumably because of differences in water source,

contributions from different flow routes, and degrees of mixing (Johns, 2006). Old Mill Spring

tends to have the highest specific conductance of the four spring outlets. The relatively high

specific conductance is most likely attributable to the proximity of Old Mill Spring to the Saline

Zone and influence of the Saline Zone on flow routes that provide a substantial percentage of the

water to that particular outlet (City of Austin, 1998). The consequences of the relatively small rise

in average salinity on the Covered Species are not known.

3.2.3 Antecedent Conditions in ITP Area

There are pre-existing conditions in the ITP Area, originating prior to the initiation of the HCP

and continuing to the present day, that have significant bearing on the affected environment of

the Covered Species and on the ability of the District to manage the Aquifer. Accordingly,

consideration of the protective enhancements and conservation measures taken under this HCP

must be framed within the context and realities of these pre-existing conditions.

Many of these conditions stem from historical patterns of development and associated water and

land use, all of which have various legal protections under other law but nevertheless influence

the quality and quantity of water discharging from Barton Springs.

50

Figure 3-8: Example of inverse relationship between springflow and water salinity at Main Springs,

expressed as specific conductance. The relatively small range of variation in specific conductance corresponds to a range in TDS of about 70 mg/L. Other

spring outlets show similar trends, but the range in salinities at other outlets differ somewhat, especially at lower flows.

Source: Herrington and Hiers (2010).

These historical land use and development trends in the ITP Area have contributed to a gradual

but progressive degradation of surface recharge quality (Mahler et al., 2013) and consequently in

the water quality of springflow discharging at Barton Springs (City of Austin, 2013); but so far

such springflow degradation has been small. The District does not have authority to manage or

control land use or the quality of Barton Springs discharges that arise from the impact of

development on surface water that recharges the Aquifer.

Figure 3-9 illustrates the history of withdrawals from all permitted wells in the Aquifer, in

association with several District milestones. Before the establishment of the District in 1987,

there was no legal authority or ability to regulate groundwater withdrawals from the Aquifer.

The Aquifer then was a readily available, sole source of high-quality water that served a growing

suburban and exurban population. Not until 1989, when the first groundwater management plan

and rules were adopted by the District and meters began to be set on permitted wells, was there

any operational permit program to manage groundwater withdrawals in this rapidly developing

area. By 1989, the estimated average pumpage in the District was about 5 cfs (0.14 m3/s).

600

620

640

660

680

700

720

740

10 20 30 40 50 60 70 80 90 100

Sp

ecif

ic C

on

du

cta

nce (

uS

/cm

)

Barton Springs Flow (cfs)

2003 - 2008

July 2008 - August 2009

51

Figure 3-9: Pumpage history showing District milestones. Actual Pumpage rates are annual averages, in cfs, for nonexempt wells in the District. Data before 1988, when wells

first began to be metered, are estimated; after 1988 data are self-reported meter readings. Source: Data through 2006

are from: Hunt et al., 2006. Data after 2006 are unpublished BSEACD data.

Before federal listing of the Barton Springs salamander as endangered in 1997, there was no

basis of reference to measure how much groundwater withdrawals or what limitation on

withdrawals would be needed for protection of the salamander population at Barton Springs. In

the mid-1990s, when the Barton Springs salamander was first described as a newly identified

species and subsequently listed as endangered, actual pumpage under approved permits or

exemptions to permits was already in the range of 5 to 6 cfs (0.14-0.17 m3/s), contributing then

to diminution of and natural variation in springflow during droughts.

From an historical perspective, the District’s intent and actions in developing this HCP are a

continuation of those the District has voluntarily and proactively followed, inasmuch as the

District’s mission was consistent with the Act’s purpose; that is, reducing water demand and/or

increasing supply that results in source-substitution during drought to preserve Aquifer water

levels and springflows, and thereby generally reduce adverse impact to the habitats of the

Covered Species. In 2004, when the District initiated the habitat conservation planning process,

the actual total pumpage from the Aquifer, under approved permits and exemptions to permits,

was about 7 to 8 cfs (about 0.2 m3/s), even though authorized pumpage under permit was just

over 10 cfs (0.28 m3/s). This HCP, which is the result of a long-term planning process, now

establishes the District’s commitment to implement actions that avoid additional adverse impacts

to the Covered Species and to minimize and mitigate those impacts of District activities that

cannot be avoided.

Drought is another, different type of pre-existing condition that is also germane to this HCP. The

ITP Area is prone to severe drought cycles, and the Covered Species are stressed “naturally” on a

variable, generally cyclic basis by drought in exactly the same way the regulated withdrawal of

groundwater by wells as a Covered Activity stress the species. (The preceding Figure 3-6, a

52

hydrograph of springflow, illustrates the cyclic nature of drought in the Area.) So the effects of

the Covered Activities, which represent a specific level of take that is analyzed in Section 5.2,

are superimposed on similar but more variable effects from a natural drought cycle that exists

regardless of whether and how much groundwater is withdrawn by wells in the Aquifer in the

ITP Area. The frequency and amplitude of this natural variability will likely tend to increase

under the influence of climate change, especially during La Nina conditions in this area. Such

changes in drought characteristics are not expected to be appreciable over the relatively short 20-

year ITP term, particularly to the extent that the Conservation Measures in this HCP and the take

assessment would be materially affected.

3.2.4 Protected Species in ITP Area

Table 3-4 lists species that are federally protected in the three counties in which the ITP Area is

located (Service database, http://www.fws.gov/southwest/es/ES_Lists_Main.cfm, accessed June

24, 2015). Most of these species are either only found in areas of these counties that are well

outside the ITP Area or otherwise are not known to exist in the ITP Area. Only the first two

species listed are known to exist in the ITP Area and may reasonably be expected to have habitat

affected by the proposed Covered Activities; and those two species are the proposed Covered

Species for this HCP.

Table 3-4: Federally protected species in Travis, Hays, and Caldwell Counties, Texas. Status is denoted as endangered (E), threatened (T), candidate (C), and of concern (D) (Service, 2014).

Group Species Common Name Status

Amphibians

Eurycea sosorum Barton Springs Salamander E

Eurycea waterlooensis Austin Blind Salamander E

Eurycea tonkawae

Eurycea nana

Typhlomolge rathbuni

Jollyville Plateau Salamander

San Marcos Salamander

Texas Blind Salamander

T

T

E

Dendroica chrysoparia Golden-Cheeked Warbler E

Birds Vireo atricapilla Black-Capped Vireo E

Grus americana Whooping Crane E

Insects

Texamaurops reddelli Kretschmar Cave Mold Beetle E

Rhadine Persephone

Heterelmis comalensis

Stygoparnus comalensis

Tooth Cave Ground Beetle

Comal Springs Riffle Beetle

Comal Springs Dryopid Beetle

E E E

Arachnids

Texella reddelli Bee Creek Cave Harvestman E

Texella reyesi Bone Cave Harvestman E Tartarocreagris texana Tooth Cave Pseudoscorpion E

Leptoneta myopica Tooth Cave Spider E

Plants Streptanthus bracteatus Bracted Twistflower C

Zizania texana Texas Wild Rice E

Fishes Etheostoma fonticola Fountain Darter E

Clams Quadrula petrina Texas Pimpleback C

53

4.0 Proposed Actions

4.1 Proposed Covered Activities

The District seeks coverage under the prospective Incidental Take Permit (ITP) for withdrawal

of groundwater from the Aquifer by well owners/operators holding a valid production permit

from the District for their groundwater supply that is managed by the District as a statutorily

mandated groundwater conservation district (GCD) in Texas. These activities result from time to

time in incidental take of the Covered Species by adversely affecting the quantity and associated

chemistry of water that is naturally discharged from the Aquifer at Barton Springs. The activities

for which the District seeks coverage arise from groundwater withdrawals from nonexempt wells

(wells producing groundwater from the Aquifer that are registered with the District and are

authorized and regulated under the District’s production-permitting program). Limits on

groundwater withdrawals apply only to District-permitted nonexempt wells. The withdrawals

from a nonexempt well are considered a Covered Activity only if the well and the permittee are

in compliance with the District’s rules, including permit conditions, prevention of waste, and

water conservation plan and drought contingency commitments. These are lawful activities with

a publicly beneficial purpose, and any associated take, as defined by the Endangered Species Act

(Act), is incidental.

Other wells in the Aquifer are statutorily exempt from permitting restrictions; these exempt

wells, while much more numerous in the District than nonexempt wells, are generally much

smaller wells used for domestic/residential and livestock purposes and are constructed such that

they are incapable of producing at a rate greater than 10,000 gallons (37,850 liters) per day

(about 7 gallons, or 26 liters, per minute).

The Covered Activities directly relate to and affect primarily the groundwater resources and the

groundwater-user community in the District. The withdrawal of groundwater from the Aquifer

by this regulated community using wells registered and permitted by the District is a principal

activity for which the ITP is sought. It is also important to the understanding of the HCP that the

District’s regulatory program is the primary vehicle for the proposed conservation measures for

the Covered Species.

The regulation of the groundwater-user community, which is accordingly also the focus of the

HCP avoidance, minimization, and mitigation measures, is described in Section 4.1.1, Regulated

Groundwater Community. The evolution and status of this regulatory program, its statutory and

regulatory authorities, and the public participation in its development are then characterized in

following subsections to provide a historical context and the current status of this vehicle under

which compliance with the ITP provisions will be assured.

4.1.1 Regulated Groundwater Community

The District is requesting coverage under the ITP for take of BSS and ABS resulting from

groundwater withdrawals from the Aquifer that are managed under its regulatory program, which

controls the conditions under which groundwater is used in the District and especially the

amount of groundwater withdrawn by permitted well owners. The uses of this managed

54

groundwater supply are characterized below in Section 4.1.1.2, Nonexempt Wells and Users.

The large majority of permitted withdrawals are dedicated to providing for public water supply

through water utilities. However, the end-user customers of these utilities are not directly

regulated by the District so they are not included in this community (Table 4-1). Their

individual use of Aquifer water is not considered part of the Covered Activities. Components of

Table 4-1: Public water system permittees using the Aquifer. Only District permitted volumes and wells reported in table. Water utilities may have additional alternate supplies or

wells permitted through other GCDs.

Permitted Volume

Water Utility Gal/Yr CFS # of Wells End-users (1) #. of Connections

(1)

Aqua Texas (Bear Creek) 12,098,000 0.051 2 276 92

Aqua Texas (Bliss Spillar) 51,500,000 0.218 21 2211 295

Aqua Texas (Leisurewoods) 88,764,000 0.376 6 1338 446

Aqua Texas (Mooreland) 6,000,000 0.025 2 156 52

Aqua Texas (Onion Creek) 36,300,000 0.154 3 696 232

Aqua Texas (Shady Hollow) 80,000,000 0.339 2 699 233

Arroyo Doble Water System 52,800,000 0.224 2 912 304

Cimarron Park Water

Company

118,000,000 0.500 2 2058 686

City of Buda 275,000,000 1.166 4 9882 3,294

City of Hays Water

Department

15,400,000 0.065 2 233 89

City of Hays Elliot Ranch 54,450,000 0.231 2 618 206

City of Kyle 350,000,000 1.484 1 24,261 8,087

City of Sunset Valley 18,590,000 0.079 1 1326 442

Creedmoor-Maha WSC 235,065,600 0.997 6 6819 2,273

Goforth Special Utility

District

350,900,000 1.488 5 15,612 5,204

Huntington Utility LLC

(SWWC)

18,000,000 0.076 1 378 126

Monarch Utility 324,400,000 1.375 4 6396 2,132

Mountain City Oaks Water

System

43,164,000 0.183 1 696 232

Mystic Oak Water Co-op 7,700,000 0.033 2 132 44

Oak Forest Water Supply

Company

25,500,000 0.108 2 321 107

Ruby Ranch Water Supply

Company

52,300,000 0.222 5 699 233

Slaughter Creek Acres Water

Company

14,000,000 0.059 2 273 91

Twin Creek Park 12,000,000 0.051 1 285 95

Village of San Leanna 31,651,200 0.134 3 497 213

Totals 2,273,582,800 9.592 82 76,774 25,208

(1) Data obtained from TCEQ Public Water System Database.

http://www14.tceq.texas.gov/iwud/index.cfm?fuseaction=showusermenu , accessed August 18, 2014.

55

the District regulatory program consist of permitting, compliance monitoring, enforcement,

assessment and administration of various District fees, user conservation planning, and user

drought contingency planning and response. The purpose of the program is to reduce

withdrawals of groundwater from the Aquifer to those minimum volumes reasonably needed by

well owners and permittees during drought and non-drought periods to conserve the water

supply for as long as possible and to maintain sufficient flows at Barton Springs to support the

Covered Species. However, the maximum reductions in water withdrawals prescribed under

this program are unable to completely avoid adverse effects on the Covered Species during

severe drought.

There are more than 1,200 water wells in the ITP Area (Figure 4-1). Some are nonexempt but

most are exempt. Many of them have existed since before the District was established in 1987.

Nearly all of them (97%) are now currently registered with the District and withdraw

groundwater from the Barton Springs segment of the Edwards Aquifer (the Aquifer). Many

more wells are located outside of the District boundaries but in the larger HCP Planning Area,

but none of those withdraw groundwater from the Aquifer. The relatively few wells

withdrawing groundwater from other aquifers (e.g., Trinity aquifers) in the ITP Area produce a

minor amount of groundwater relative to Aquifer withdrawals. Regardless of the aquifer used,

most wells in the ITP Area and the Planning Area serve small-volume users. They are typically

domestic wells for individual households that are exempt from permitting and therefore are not

regulated or monitored by the District as to the amount of water withdrawn. Groundwater

withdrawals from these unregulated, smaller-volume wells are not Covered Activities.

The District classifies its registered wells into four major categories, which determine whether

and specify how the District regulates its groundwater use (BSEACD, 2012). These are

summarized in Table 4-2 and are further characterized in subsections below.

Table 4-2: Estimated/authorized groundwater withdrawal in the ITP Area by withdrawal type. Exempt use is estimated from geospatial analysis (Banda et al., 2010); nonexempt uses are 2013 use by the type of

permit that authorizes withdrawal. The Nonexempt Historical withdrawal includes 91,525 thousand gallons (346.4

million liters) per year from Trinity Aquifer permits; the remainder is from Edwards Aquifer permits.

Withdrawal Type Number

of Wells Regulated by

District

Estimated/Authorized

Withdrawal

1,000 gal./Year CFS

Exempt Use 997 No 105,000 0.4 Nonexempt Domestic Use 103 Yes 49,500 0.2 Nonexempt Historical 110* Yes 2,462,513 10.4 Nonexempt Conditional 30* Yes 348,700 1.5 *Some wells may have authorized withdrawal under both historical and conditional production permits. Numbers

shown are for the dominant type of authorized withdrawal.

56

Figure 4-1: Location of Aquifer wells in ITP Area and use type. Except for groundwater withdrawals from wells authorized as Nonexempt Domestic Use (Table 4-2), withdrawals

from domestic, livestock, monitor, and closed-loop wells are exempt from permitting. The other use types are

nonexempt and require a District permit to authorize withdrawals. Source: BSEACD wells database, 2013.

57

4.1.1.1 Exempt Wells and Users

An exempt well by State law is not subject to the District’s permitting program and therefore has

no authorized withdrawal limit set by the District. However, they are registered by the District

and are subject to District Rules related to well-construction standards and avoidance of “waste”

as defined by statute.

Individual exempt wells generally withdraw only small volumes of groundwater. An exempt

well is generally defined by statute as a well that is used solely to supply domestic use or to

provide water for livestock or poultry if the well is: (1) incapable of producing more than 10,000

gallons (37,850 liters) of groundwater a day, and (2) located or to be located on a tract of land

larger than 10 acres (4.0 hectares). Exempt wells include by definition several other use types:

closed-loop injection wells, dewatering wells, oil and gas wells, and monitor wells. There are no

oil-and-gas supply wells or dewatering wells registered in the District and, because injection and

monitor wells are not designed for the purpose of groundwater withdrawal, aggregate

withdrawals from these use types are negligible.

Exempt wells are generally used as water supplies for livestock (including windmill-powered

wells) and/or for residences on large-tract household, ranch, or farm lands. The District recently

estimated on the basis of geographic information system (GIS) analysis of categorized land

parcels not in water utility service areas that there were about 1,000 exempt wells in the District,

but they produced only about 4% of the total volume of groundwater withdrawn by all wells in

the District (Table 4-2). Further, the number of wells in service and amount of exempt

withdrawals are likely decreasing as these wells age, deteriorate, and are abandoned, and as the

ITP Area becomes more developed with centralized water systems (Banda et al., 2010). The

specific number of the wells being abandoned typically goes unreported and therefore is difficult

to estimate. Most existing exempt wells were in place at the time the District was formed in

1987. Very few new wells in the District meet all the criteria to be exempt.

Exempt wells are capable of only limited withdrawals because they are generally equipped to

produce no more than 10,000 gallons (37,850 liters) per day or the equivalent pumping rate of

about 7 gallons per minute (0.0004 m3/s). Withdrawals are limited by well size and equipment

rather than by regulation. Actual withdrawals are estimated to be more typical of regional

domestic-use withdrawals and are substantially less than the 10,000-gallon-per-day (0.63 m3/s)

withdrawal-capacity limitation (Table 4-2). Actual withdrawals are not known because exempt

wells are not usually metered, and owners/operators are not required to report water use or

charged for water use at any time. Exempt wells do not have the permits that are used by the

District as the vehicle to specify User Conservation Plan (UCP) and User Drought Contingency

Plan (UDCP) requirements, so mandatory, enforceable drought-period curtailments are not

applicable to them. Therefore, under Service regulations, exempt wells cannot be a Covered

Activity for the HCP.

Even though withdrawals from exempt wells by State law are not subject to limitation by the

District, the total groundwater withdrawal by exempt wells does affect the allowable amount of

water to be withdrawn by other wells during Extreme Drought conditions.

58

4.1.1.2 Nonexempt Wells and Users

Withdrawal by all nonexempt wells in the Aquifer is regulated through District permits and is a

Covered Activity. Permits are the vehicles for implementing the District’s drought rules that

constitute its Drought Contingency Plan.

All permittees must adopt UCPs and UDCPs, which are integral, mandatory parts of every

permit. Templates for UCPs and UDCPs that have been developed by the District and made

available to its permittees as guidance are included in Appendix E. UDCPs in particular are

central to the District’s drought management program. This program involves a declaration by

the District Board of the severity of groundwater drought on the basis of actual Aquifer

conditions, as defined by the District’s Drought Trigger Methodology developed for this HCP.

(See Appendix F for details on the drought trigger methodology, and Appendix G for the rule-

based definitions of the various groundwater drought stages used by the District for drought

management.) Permittees are required to curtail their monthly groundwater use according to the

declared drought stage and their approved baseline volume for a given month, as specified in

their UDCP. All individual permittees are required to report their actual groundwater use

monthly to the District. The District uses these data to assess compliance with monthly UDCP

requirements and to initiate pre-enforcement and enforcement actions, if and as warranted,

during drought; and to evaluate whether permittees have exceeded their annual authorized

withdrawals.

The requirements of UCPs and UDCPs and the penalties for noncompliance are specified by

District Rules and the District’s Board-approved Enforcement Plan; they are legally enforceable

by the District. The District’s enforcement scheme includes assessment of daily penalties, up to

$10,000 per day, that are indexed to the amount of authorized use, the degree of noncompliance,

and drought stage. More information on the District’s Enforcement Plan is in Section 6.5.1.4,

District Enforcement Program. The District typically achieves immediate compliance for

egregious and recurring violations of monthly pumping limits through agreed settlement orders.

Such orders apply early resolution incentives through a prescribed reduced percentage of

monetary penalties, applicable sanctions, and compliance requirements. But enforcement can

also be achieved through litigation in district court, where the full amount of the penalty then

becomes a matter before the court. The District has never had to instigate this latter step to

achieve satisfactory compliance by permittees.

The relationship between production permit type and degree of curtailment under specified

drought conditions is summarized in Table 4-3. The various regulatory drought stages and

related curtailment provisions of the District’s drought management program are explained in

greater detail in Appendices F and G.

59

4.1.1.2.1 Nonexempt Domestic-Use Wells and Users

A nonexempt domestic-use (NDU) well13 is a well that is used by, and connected to, a household

for personal needs or for household purposes such as drinking, bathing, heating, cooking,

sanitation or cleaning, and landscape irrigation but that does not meet the criteria for exemption

from permitting. These wells must be on a single-ownership plot smaller than 10 acres (4.0

hectares) that contains a household. (If on a tract larger than 10 acres, these wells typically

would be exempt.) NDUs typically operate under a “general permit by rule” which applies only

to wells that:

1. Are used only for domestic purposes;

2. Were drilled and completed on or after August 14, 2003;

3. Are not in an area in which a water supplier has a valid certificate of convenience and

necessity (CCN) to service the area, unless that water supplier is not readily able to

supply water;

4. Have a requested annual pumpage that does not exceed 500,000 gallons (5,185 liters per

average day) per household (actual use is typically considerably less than authorized use);

and

5. Have a requested volume that does not exceed acceptable standards for both domestic use

and landscape irrigation.

NDU wells are required to have water meters and the owners must periodically report water use.

Presently, no water use fee is charged for NDU wells for water withdrawals, but the District does

charge their users a small, one-time administrative permit application fee. As of the end of fiscal

year 2017, approximately 103 NDU (now LPP) wells were in the Aquifer (Table 4-2).

4.1.1.2.2 Other Nonexempt Wells and Users

Most other nonexempt wells not authorized by general permits are required to have individual

production permits from the District and to be metered, and owners/operators are required to pay

an annual water use fee on the basis of their authorized use and to report actual water use

monthly. In 2014, nonexempt well users paid water use fees ranging from $0.17 to $0.46 per

1,000 gallons (3785 liters) of water used, depending on the type of permit (historical or

conditional, as described in the following subsections). The District has about 90 individual

production permit holders in the ITP Area, not including NDUs but including the public water

supply wells in Table 4-1. An estimated 96 percent of the total volume of groundwater

withdrawn in the District is now by nonexempt wells.

These individually permitted wells are categorized by use type: agricultural, commercial,

industrial, irrigation, and public water supply (Figure 4-1). Each permittee may have multiple co-

located wells under a single permit. The permittees include churches, office parks, quarry

13 In late 2015, the NDU general permit was replaced by a new general permit called the Limited Production Permit

(LPP), which will be used for certain wells in both Edwards and Trinity Aquifers. While the LPP’s administrative

requirements differ somewhat from those of the NDU, its applicability and restrictions are substantially the same as the

NDU. The substitution of LPP for NDU has no effect on the habitat characteristics of the Covered Species.

60

operations, schools, community athletic fields, golf courses, municipalities, and water-supply

utilities. The largest use by far is for public water supply. Type of use is one determinant of the

provisions that the District Board considers when it examines permittees’ UCPs and UDCPs.

An example of a public water supply UDCP is the City of Buda’s UDCP (http://tx-

buda.civicplus.com/DocumentCenter/View/103). The City of Buda amended its UDCP in

early 2012, as did other nonexempt permittees, to comply with 2011 amended requirements

of the District’s Rules and Bylaws, which called for enhanced curtailments or reductions of

40% of permitted pumpage during a District-declared Stage IV Exceptional Drought. The

District amended its Rules again in October 2012, requiring even greater curtailment to 50%

of permitted pumpage during a District-declared Emergency Response Period, to implement

a prospective HCP measure and to achieve the newly established Desired Future Condition

(DFC) of the Aquifer. All permittees will be required to amend their UDCPs again to

accommodate the new 50% curtailment, which will become effective two years after the

Rules were adopted; that is, October 11, 2015.

There are two primary types of individual production permits for nonexempt wells: Historical

Production Permits, and Conditional Production Permits. Each type has different impacts on the

habitats of the Covered Species.

Wells with Historical Production Permits

Withdrawals from existing wells that were nonexempt and registered with the District as of

September 9, 2004, were designated with Historical-use Status and authorized under permits

designated as Historical Production Permits. Most of the authorized withdrawals from the Aquifer

are authorized under such permits. Withdrawals under Historical Permits are required to curtail

monthly pumpage by 20, 30, and 40 percent during Stage II-Alarm, Stage III-Critical, and Stage

IV-Exceptional Droughts, respectively, and after October 11, 2015, by 50% during a Board-

declared Emergency Response Period. (These groundwater drought status terms are defined and

discussed in Appendix D, and the curtailment program is summarized in Table 4-3.) Historical

Permits amended after September 9, 2004 to increase authorized withdrawals, and all new

production permits after that date, are subject to Conditional Production permitting rules for the

increase.

Wells with Conditional Production Permits

Withdrawals from Aquifer wells that received initial permits or existing Historical Permits that

have been amended to increase authorized withdrawals after September 9, 2004, were authorized

under permits designated as Conditional Production Permits. This date was established by the

Board following the findings and conclusions of the District’s Sustainable Yield Study (Section,

3.2.2.1.2, Sources and Implications of Variation in Springflow at Barton Springs). The distinction

from Historical Production Permits is important, because unlike those permits, withdrawals under

Conditional Production Permits are authorized by the District only on an interruptible-supply basis.

That is, the water supply under that permit is authorized only on the condition that the allowed

monthly withdrawals will be increasingly curtailed during prolonged groundwater drought, up to

and including complete cessation of pumping during Extreme Drought (Table 4-3). These permits

have UDCPs that provide for mandatory curtailments of 50, 75, or 100 percent of their authorized

monthly withdrawals during deepening stages of declared droughts. The District has further

61

Table 4-3: Mandatory curtailment of water withdrawals. Curtailments established for different well permit types, aquifers, and drought conditions. (Curtailment expressed as percentage of authorized monthly water

withdrawal in designated drought stage. For example, freshwater Edwards Aquifer historical permittees would be required to curtail their authorized monthly

withdrawal by 30% during Stage III Critical Drought.)

Drought Curtailment Chart

Aquifer Edwards Aquifer Trinity Aquifer

Management Zone Eastern/Western Freshwater Saline Lower Middle Upper Outcrop

Permit Type

Historical Conditional Hist. Hist. Hist. Hist. Hist.

Class A Class B Class C Class D

Dro

ught

Sta

ges

No Drought 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%

Water Conservation

(Voluntary) 10% 10% 10% 10% 10% 0% 10% 10% 10% 10%

Stage II Alarm 20% 20% 50% 100% 100% 0% 20% 20% 20% 20%

Stage III Critical 30% 30% 75% 100% 100% 0% 30% 30% 30% 30%

Stage IV Exceptional 40% 50%1 100% 100% 100% 0% 30% 30% 30% 30%

Emergency Response

Period 50%3 >50%2 100% 100% 100% 0% 30% 30% 30% 30%

Percentages indicate the curtailed volumes required during specific stages of drought.

1 Only applicable to NDUs/LLPs and existing unpermitted nonexempts after A to B reclassification triggered by Stage IV-Exceptional Drought

declaration

2 Curtailment > 50% subject to Board discretion

3 ERP (50%) curtailments become effective October 11, 2015. ERP curtailments to be measured as rolling 90-day average after first three months

of declared ERP.

62

categorized Conditional Permits by whether they initially existed or were in process on April 27,

2007 (Class A Conditional Permits), or after that date but before March 24, 2011 (Class B

Conditional Permits), or on or after March 24, 2011 (Class C Conditional Permits). A fourth

conditional-use category, Class D, is reserved for use in supplying water from the Aquifer to

future aquifer storage and recovery facilities, but only during non-drought periods. Class B, C,

and D Conditional Permits have an accelerated curtailment schedule during drought. Certain

Class A permits (generally those with access to alternate supplies) will be permanently converted

to Class B permits upon declaration of a Stage IV-Exceptional Drought. All conditional

production wells are expected under their permit terms to have ceased pumping during Stage IV-

Exceptional Drought or deeper drought, which is the drought condition that is of most concern to

the sustainability of the Covered Species.

4.1.2 Historical Perspective of Covered Activities

4.1.2.1 Evolution of Regulatory Program

The drought of the 1950s has become the basis for long-term water-resource planning in most of

Central Texas. This drought of record (DOR) signified that both surface-water and groundwater

management programs needed to incorporate drought management as a principal goal. In the

ITP Area, the DOR produced the lowest recorded flows at Barton Springs, with the lowest

measured daily flow of 9.6 cfs (0.27 m3/s) and the lowest monthly mean flow of 11 cfs (0.31

m3/s). At that time, most water supplies in the area came from surface water. The USGS

estimated that average groundwater use of the Barton Springs segment of the Edwards Aquifer

then was only 0.66 cfs (0.019 m3/s; Slade et al., 1986). So the lowest total monthly mean

discharge from the Aquifer during the DOR was about 11.7 cfs (0.33 m3/s).

But the area has grown rapidly since then and much new development was beyond the reach of

centralized surface water-supply systems of the COA or the Lower Colorado River Authority

(LCRA). The Aquifer provided a readily accessible, high-quality, and cheap source of water for the

area, and its use by individual residential users, developments, and small suburban cities increased

rapidly. But there was no authority that could implement a drought management program that could

protect the water levels in the Aquifer or the springflow at Barton Springs.

When the District was formed in 1987, there was no restriction of any kind on withdrawals from the

Aquifer or any other groundwater in the region. In fact, it was concern over that fact that led to the

creation of the District. The District put into place its initial permitting program in 1989, which

became fully implemented in 1990. This program was successfully used to identify and regulate

withdrawals within the District, including notably a relatively novel drought management program

with curtailments of as much as 20% of authorized withdrawals and based on declared drought

stages (although those stages were then defined differently than now). But after a decade or so,

withdrawals from the Aquifer to serve the fast-growing area on the then southern fringe of Austin

had increased to the point where the impact of withdrawals on Barton Springs during a recurrence of

the DOR became a concern. The District undertook a study (Smith and Hunt, 2004) on the basis of

the best science then available to ascertain the sustainable yield of the aquifer. Findings of the study

indicated that during a recurrence of the DOR, authorized withdrawals, if un-curtailed, would cause

yield problems with almost one-fifth of the wells in the District, and Barton Springs flow would be

reduced to near zero (Smith and Hunt, 2004).

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These findings confirmed the need for changes in the District’s regulatory and drought management

program and further, the need for more accelerated and larger curtailments. Awareness of the

findings also marked the end of the first-generation groundwater management program that is

denoted herein as the “pre-HCP program.” Under that program, there was no upper limit on total

withdrawals under permit, and drought curtailments were linked to percentiles of monthly flow at

Barton Springs: no curtailment when flow was above the 50th percentile (51 cfs); 10% curtailment

below the 50th percentile; 20% curtailment below the 25th percentile (30 cfs); and 30% curtailment at

or below 10 cfs (0.28 m3/s) (which has only been reached during the DOR). In practice, little

enforcement of these curtailment limits actually occurred, and the actual curtailments achieved then

were likely considerably smaller while withdrawals grew steadily. A more effective drought

management plan became a priority in the early 2000s.

The need for additional resources to help define the new drought management program and its

ecological benefits led to several consultations with the U.S. Fish & Wildlife Service (Service) and

eventually to the first HCP grant awarded to the District in 2004, marking the initial phase of the

HCP. This work produced a more rigorous and meaningful drought trigger methodology and a more

rigorous and stringent drought management program that was based on the imposition of a junior-

senior permitting scheme that included conditional-use permits with interruptible production, as well

as a preliminary integrated HCP and Environmental Impact Statement (EIS) document. Significant

droughts in 2006, 2008–09, and 2011 provided the impetus for a series of amendments to the permit-

based drought rules, such that the drought management program became one of, if not the most,

stringent in the State. This regulatory program was developed under the Texas Open Meetings Act

and in accordance with the statutory requirements for rulemaking, providing multiple opportunities

for public and stakeholder input at each rulemaking step.

In the second phase of HCP development, pioneering experimental work concerning DO

concentrations and salamander mortality (Poteet and Woods, 2007; Woods et al., 2010) was done.

This work (Section 5.2.1, Experimental Assessment of Salamander Responses to Changes in Water

Chemistry Related to Springflow), funded by the District HCP, strongly suggested that Barton

Springs flow needed to be still higher during Extreme Drought; and therefore aggregate withdrawals

needed to be less than what could be achieved under the then-current regulatory program. This

result informed the District’s 2010 recommendation to the Groundwater Management Area (GMA)

10 joint regional planning committee for a new, statutorily mandated set of groundwater planning

objectives called Desired Future Conditions (DFC) of the Aquifer. A consensus of the GMA

considered DFCs to be protective of the Aquifer, both as a water supply and as habitat for the

Covered Species, and to be achievable (TWDB, (2014). The Aquifer now has two DFCs: (1) an

effective upper limit on withdrawals of 16 cfs (0.45 m3/s) (of this 16 cfs, only the historical non-

exempt use amount of 10.2 cfs, plus a minor amount of exempt or exempt-like use would be

authorized to pump any groundwater during drought conditions that would lead to take, and 2 cfs of

the balance is reserved for permitted ASR source water), to limit the acceleration of the onset of

drought conditions in the Aquifer resulting from withdrawals; and (2) maintenance of springflow not

less than 6.5 cfs (0.18 m3/s) during a recurrence of DOR conditions. Using the lowest total monthly

discharge (springflow and a small amount of pumpage) reported during the DOR, 11.7 cfs, for

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reference, total withdrawals from all wells in the Aquifer during a recurrence of DOR conditions

need to be no more than 5.2 cfs (0.15 m3/s) on an average annual basis to achieve those DFCs.14 The

District’s then-current (2012) regulatory program, which was developed after numerous informative

consultations with other advisory groups and stakeholders, could produce a minimum of 6.7 cfs

(0.19 m3/s) of pumping, rather than the 5.2 cfs needed.

In early 2012, the District initiated a stakeholder process to explore strategies to close the 1.5 cfs

(0.042 m3/s) “gap” that then existed between the modeled maximum 5.2 cfs of average annual

pumping allowed during DOR conditions (MAG for the DOR DFC) and the 6.7 cfs of pumping

authorized after mandatory pumping curtailments under the District drought management

program. That process culminated in late 2012 with phased measures that were incorporated, as

feasible, into the regulatory-based drought management program. These measures were also

accompanied by a continuing commitment to promote the long-term development of alternative

water supplies when and where feasible, and where such supplies would benefit management of

the Aquifer during severe drought.

With strategies in place, the District anticipated that the level of aggregate curtailment needed to

achieve the DFC, while very stringent, would be achievable. The gap has already been

successfully reduced from about 1.5 cfs (0.042 m3/s) in 2012 to about 0.3 cfs (0.008 m3/s) to date

(2017). The District is confident that even this small gap will be gradually reduced and then

completely closed because of the continuing ongoing efforts by both the District and its

permittees related to: incentives to retire permitted historical withdrawals; rules requiring higher

levels of curtailment during Extreme Drought; rules incentivizing higher curtailments during

severe drought in exchange for proportional increases in permitted withdrawals during non-

drought; historical experience with some permittees that voluntarily substitute available

alternative supplies for authorized Aquifer withdrawals during severe drought; and "right-sizing"

provisions (ensuring permitted amounts are no larger than those actually required for the

permitted use and permit conditions). Subsequent rounds of DFC planning may also incorporate

improved aquifer modeling to better account for all recharge sources (e.g., urban recharge) and

continuing efforts to develop and extend alternative supplies to historical-production permittees

to enable their substitution of Aquifer withdrawals so that a no-gap condition exists during the

ITP term. As a GCD in Texas, the District has a legal and statutory obligation to ensure that the

Extreme Drought DFC is achieved by its regulatory program, and it will be monitoring MAG

and DFC status on a continuing basis to ensure compliance. In aggregate, this mandatory DFC-

based regulatory program and multi-dimensional groundwater management approach are core

components of the HCP.

Further, achieving the Extreme Drought DFC is judged more likely since actual withdrawals that

affect springflow are typically less than the authorized amount of withdrawals to which the MAG

corresponding to the DFC is referenced. This difference between actual and authorized

pumpage, which has been noted to occur even in severe droughts, provides an additional buffer

in assuring the achievement of the DFC. As necessary and at the Board’s discretion, some

14 The 5.2 cfs (0.15 m3/s) is the modeled available groundwater (MAG) which is the estimated maximum amount of

annual withdrawals allowable while preserving the minimum Extreme Drought DFC of 6.5 cfs (0.18 m3/s) as

determined by groundwater availability modeling.

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additional rulemaking and policy development, both currently undefined, as well as individual,

targeted stop-gap Board Orders may also be used, providing even further assurance that the gap

will not exist and the springflow-based DFC will be achieved in the future on a sustained basis.

In 2011, the Texas Legislature passed Senate Bill 332, reinforcing the private property ownership of

groundwater in place and also requiring that groundwater conservation be balanced by withdrawing

the maximum amount of water feasible. Then the Texas judicial system issued two decisions, one

by the Supreme Court in mid-2012 in EAA v. Day (369 S.W.3d 814 (Tex. 2012)) and another by the

4th Appellate Court in early 2013 in EAA v. Bragg (No. 04–11–00018, 2013 WL 5989430 (Tex.

App.—San Antonio, November 13, 2013)), that held unequivocally the possibility of compensable

regulatory takings by groundwater regulation, even if a groundwater conservation district (GCD) is

acting fairly and within its authority and rules. These two cases and their implications for

groundwater management are discussed in more detail in Section 7.2.1.7, Recent Texas Court

Decisions and Aftermath.

In 2015, House Bill 3405 was enacted, requiring the District to annex that part of Hays County in

which the Trinity Aquifer was not subject to regulation by any GCD. This legislation created the

Shared Territory described in Section 3.1.3, BSEACD Jurisdictional Area; as intended by the bill,

the District will regulate the Trinity Aquifer in this area but not the Edwards. No part of the Aquifer

is located in the Shared Territory, and the ITP Area excludes all portions of the Shared Territory. So

pumping in the Shared Territory created by HB 3405 is not a Covered Activity under this HCP.

4.1.2.2 Changes to Pre-HCP Baseline

Taken together, the internal and external developments in 2011–15 described in the preceding

subsection indicate the District has about reached the practical limit of what it can legally and

statutorily accomplish with its regulatory-based demand reduction program, without incurring

potentially catastrophic legal and financial risks associated with compensable regulatory takings.

The District considers the program as currently proposed to represent minimization and mitigation

“to the maximum extent now practicable,” subject to possible future changes via statutory and

adaptive management processes. The Service will consider and determine what is practicable in its

Findings documentation as part of its intra-Service consultation process.

The beneficial effect of the District’s drought-management regulatory program on springflow is

shown in Figure 4-2. The figure shows computed Barton Springs flow with only exempt pumpage

for the period of record and for comparison the springflows with 2014 nonexempt withdrawals

authorized by the District (11.6 cfs; 0.33 m3/s) as regulated alternatively by the two groundwater

management scenarios; that is, before and after HCP measures were in place. The figure also shows

the springflow that would have existed during the period of record with only the small amount of

unregulated groundwater withdrawals from exempt wells, designated as the “exempt-only pumping”

scenario. The springflow of the exempt-only pumping scenario (which includes the DOR) excludes

the effects of nonexempt withdrawals that actually occurred each month during the period of record.

The springflow of the exempt-only pumping scenario is the baseline for comparison in this HCP.

The springflow of the pre-HCP scenario in Figure 4-2 shows how the baseline springflow would

have changed by regulating permitted withdrawals with only the curtailment program as it existed

before 2004, when the District’s conditional permitting program was instituted and the HCP

http://elibraries.westlaw.com/find/default.wl?mt=Westlaw&db=4644&findtype=Y&tc=-1&rp=%2ffind%2fdefault.wl&spa=Bickers-3000&ordoc=2031937163&serialnum=2027195473&vr=2.0&fn=_top&sv=Full&tf=-1&referencepositiontype=S&pbc=C9563F50&referenceposition=843&rs=EW1.0

66

development project was initiated. (At that time, there was 10.2 cfs of authorized-nonexempt use;

with 0.45 cfs of exempt use, total withdrawals were about 10.6 cfs, or 0.300 m3/s). The springflow

of the HCP scenario in Figure 4-2 reflects a regulatory program with the full complement of

proposed HCP measures in place.

To facilitate comparison, both the pre-HCP and the HCP scenarios in Figure 4-2 are applied to the

same rate of withdrawal, that is, 11.6 cfs, the 2014 total permitted in 2014 (including both historical

and conditional withdrawals). Each of those scenarios restricts withdrawals during drought in

different ways and to different degrees, which in turn affects springflow differently. However there

is another important distinction between the two scenarios that is not reflected in the springflow

hydrograph of Figure 4-2. The two scenarios would place substantially different management

restrictions on total withdrawals from the Aquifer that ultimately could be authorized in the future.

In the pre-HCP scenario, there is essentially no upper limit on the amount of water that could be

authorized to be withdrawn from the Aquifer to meet demand, which would accelerate the onset of

drought conditions in the Aquifer and reduce springflow even further during future droughts even

with the pre-HCP curtailments. For example, Scanlon et al. (2001) indicated that by 2050,

unregulated Aquifer use would increase to 210% of what it was in 2000, or about 19.6 cfs (0.55

m3/s) without effective limitation, even during a DOR recurrence. Without the District’s current and

proposed regulatory program, the increase in total pumpage from the Aquifer would have continued

to be largely unchecked during the course of the ITP.

The proposed HCP program provides a regulatory mechanism to restrict the total amount of

water authorized to be withdrawn from the Aquifer in the future, while providing for increased

use of the Aquifer only during non-drought conditions. Only the proposed HCP program’s

management scheme has an upper limit on authorized withdrawals, at 16 cfs (0.45 m3/s), which

has been established by the District Board to allow an acceptable level of acceleration into

drought; that is, approximately one month. In other words, a 16-cfs upper limit on withdrawals

would ensure that the Aquifer reaches drought conditions no sooner than one month earlier than

otherwise. The pre-HCP program imposes no such cap. Only the HCP program differentiates

authorized conditional pumpage (pumpage greater than 10.2 cfs, or 0.29 m3/s) from authorized

historical pumpage (pumpage up to 10.2 cfs). Conditional pumpage is interruptible and subject

to accelerated curtailment up to and including complete curtailment. Historical pumpage is not

interruptible but is subject to curtailment that provides a minimum firm-yield supply during

Extreme Drought. Thus, the proposed HCP program has an assured regulatory limit on all

pumpage to no more than 5.2 cfs (0.15 m3/s, including 0.5 cfs, or 0.01 m3/s, of exempt use)

during a DOR recurrence. The pre-HCP program does not. These differences mean that the

springflow shown in Figure 4-2 under the HCP Scenario does not depend on what additional

total pumpage is authorized, while the springflow under the pre-HCP Scenario may be further

reduced from that shown in the figure, especially during severe drought.

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Figure 4-2: Computed Barton Springs flow, 1917–2013, under three conditions: exempt-only pumping, pre-Habitat Conservation Plan

pumping, and Habitat Conservation Plan pumping. Computed springflow showing the effects of two groundwater management scenarios relative to springflow that would have existed with only

withdrawals from exempt wells. The HCP management scenario is more effective than the pre-HCP management scenario in preserving springflow

under low-flow conditions, when the Covered Species are most stressed by severe drought.

0

20

40

60

80

100

120

140

Exempt-only pumping

Pre-HCP pumping

HCP pumping

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4.1.3 Statutory and Regulatory Authorities for Covered Activities

and Integrated Conservation Measures

The District’s statutory authority and purpose are to preserve, conserve, and protect the groundwater

resources of the District. A principal dimension in meeting this legislative charge is implementation

of a regulatory program to manage the withdrawal of groundwater from the Aquifer during both

drought and non-drought conditions. The District HCP relies on this authority, as elaborated in this

section.

The powers vested in the District stem from the laws enacted by the State of Texas, namely Senate

Bill 988, 70th Regular Session, the District’s enabling legislation now codified in the Special District

Local Laws Code, Chapter 8802, Barton Springs/Edwards Aquifer Conservation District; and the

Texas Water Code, Chapter 36. Chapter 36 is the over-arching statutory authority for virtually all

GCDs in Texas.

Except as specifically altered by the supervening statutory authority of enabling legislation, Chapter

36 establishes how groundwater is managed and administered by GCDs. Additional and revised

authorities and requirements affecting the District were enacted by the Texas Legislature since the

District’s enabling legislation in 1987. A listing of these bills with a brief summary description is

provided in Table 4-4.

The District is governed by a five-member Board of Directors elected by the voters in five single-

member precincts (Figure 4-3.) The internal precinct boundaries may change through redistricting,

which is required with any change in the external boundaries or with each decennial census. For

example, as a result of the annexation of the Shared Territory, redistricting was required and

occurred in mid-2016. Upon decennial redistricting, the Board shall place no more than two of the

precincts entirely within the full-purpose boundaries of the COA, as the boundaries exist at that time.

Such redistricting is a normal, expected part of the District’s governance and changes in director

precinct boundaries (and directors) are neither Changed Circumstances under the HCP nor proposed

to require ITP amendment. Each elected Board ensures the management and policies of the District,

including its groundwater management program, are aligned with local interests and are sworn to

comply with all applicable federal, state, and local laws, which will include the prospective ITP and

HCP.

Under its statutory powers, the District’s Board has adopted and from time to time amends a set of

Rules and Bylaws (BSEACD, 2016), under which it has registered all known wells and has

permitted those certain wells that are subject to its jurisdiction and are not exempted from permitting

by law or rule. Rule changes that support or are otherwise not inconsistent with the biological goals

and objectives of the District HCP in Section 6.1, Biological Goals and Objectives of the HCP, are

also proposed to be neither Changed Circumstances nor a requirement for an amended ITP.

Important to the success of the HCP is the fact that most (approximately 95%) of the groundwater

withdrawn from the Aquifer is nonexempt and therefore actively managed under District permit

authorizations.

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Figure 4-3: Barton Springs/Edwards Aquifer Conservation District 2016 director precinct

boundaries. Board members are elected by popular vote of all residents within their single-member precincts. These

precinct boundaries were established through re-districting in mid-2016 to accommodate the legislated

annexation of the Shared Territory in southern Hays County.

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Table 4-4: Legislation affecting District authority.

Year Bill No. Captioned Subject(s)

1987 SB 988

Related to validating the creation of the Barton Springs/Edwards Aquifer

Conservation District and amending the powers and duties of that district;

providing the authority to impose penalties and water use fees; and reducing the

authorized level of taxation.

1989 SB 1212 Relating to the creation, administration, and operation of underground water

conservation districts and of management and critical areas.

1997 SB 1 Relating to the development and management of the water resources of the State;

providing penalties. (aka the “omnibus water bill”).

2001 SB 2 Relating to the development and management of the water resources of the State,

including the ratification of the creation of certain groundwater conservation

districts; providing penalties.

2005 HB 1763 Relating to the notice, hearing, rulemaking, and permitting procedures for

groundwater conservation districts (was expanded to include groundwater

planning provisions).

2007 SB 3 Relating to the development, management, and preservation of the water

resources of the State; providing penalties.

2007 SB 747 Relating to the authority of the Barton Springs/Edwards Aquifer Conservation

District to charge certain fees and limit groundwater withdrawals during drought.

2011 SB 433 Relating to the de-annexation of land in Bastrop County by the Barton

Springs/Edwards Aquifer Conservation District.

2013 SB1532

Relating to TCEQ’s power to authorize certain injection wells within BSEACD’s

external boundaries but not in its territory that transect or terminate in the

Edwards Aquifer (to enable ASR in Edwards and desalination concentrate

disposal in underlying formations)

2015 HB 3405 Relating to the authority of BSEACD to regulate certain non-Edwards wells in

Hays County (via annexation of otherwise unprotected areas)

The withdrawal limits now imposed on wells in the District have been adopted and implemented in

an effort to protect groundwater resources and reduce drought-stage groundwater withdrawals, to

sustain water supplies for its permittees, and to maintain springflow at Barton Springs, to the

maximum achievable extent, subject to the limits of reasonable regulation and legal liability. The

most current set of Rules and Bylaws pertaining to Barton Springs flow are on the District’s website

under the tabbed menu heading, “About Us/Governing Documents” (http://www.bseacd.org/about-

us/governing-documents/). Information on the permitting program and other regulations applicable

to the Barton Springs segment of the Edwards Aquifer is under the “Regulatory Program” menu

(http://www.bseacd.org/regulatory/).

The Rules and Bylaws are adopted in accordance with the District Management Plan (BSEACD,

2017), which is reviewed, revised as warranted, and readopted at least every five years. It was most

recently amended and adopted by Board Resolution on September 28, 2017, and approved by the

TWDB on November 21, 2017. (The Management Plan, in turn, is prepared in accordance with

Texas Water Code, Chapter 36, Section 1071, and TWDB requirements under Texas Administrative

Code, Chapter 356, Sections 5 and 6.)

The District’s authority mainly relates to groundwater quantity; it has only limited and indirect

authority to protect groundwater quality. Its ability to offer such protection derives primarily from

its authority to avoid and minimize waste of groundwater, which by definition includes

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contamination or pollution of water that is within or recharges the Aquifer and that harmfully alters

the character of the groundwater. GCD regulation to prevent the harmful alteration of groundwater

more typically involves the prevention of pollution through the enforcement of well construction

standards and setback distances from potential sources of contamination. The District explicitly

does not have the authority under its enabling legislation to regulate land use, including subdivision

restrictions.

As a practical matter, most groundwater-quality protective measures are afforded by other regulatory

entities with more explicit authority to regulate land-use activities, even for groundwater within the

District’s jurisdictional area. The programs and entities that are involved in groundwater quality

protection are discussed in Appendix H.

4.1.4 Public Participation in Developing Covered Activities and

Integral Conservation Measures

As a political subdivision of the State of Texas, the District is obligated to operate transparently and

to routinely involve the public in its normal business operations, with only a few statutorily

prescribed exceptions. Further, the “Five Point Policy” developed by the Service as

recommendations and guidance in preparing HCPs, which was used by the District in developing

this HCP and is now incorporated in the Service’s “HCP Handbook” (Service and NMFS, 2016),

prescribes “opportunities for public participation” as one of the five elements.

During the period in which this HCP was being developed, the District held more than 80 Board

meetings, including work sessions, in which the HCP was specifically identified as a discussion item

on the agenda. These were all public meetings under the Texas Open Meetings Act, with agendas

posted with the Texas Secretary of State (until September 2011), at county courthouse bulletin

boards, and at the District office typically 6 days (and no less than 3 days) in advance of the meeting.

With few exceptions, all of these Board meetings offered opportunity for public comment and

participation as desired on the ongoing HCP evolutionary process, including consideration of both

the regulatory program and the proposed conservation measures, and their documentation. The

District has maintained a webpage dedicated to the HCP since 2007, which has been used as a

communication vehicle for HCP project progress and documentation.

The District has provided additional opportunities for structured participation by stakeholders and

the public, and it has considered perspectives of other knowledgeable members of the scientific

community in developing the HCP:

• During the active investigation and development stages of the HCP, the District used from

time to time several external advisory groups to assist the District’s efforts, including:

a. A hydrogeological/technical advisory committee, in the evaluation of aquifer drought

management options and drought trigger methodologies;

b. A biological/technical advisory committee, in the planning and monitoring of needed

research on stressor-responses, the effectiveness of potential conservation measures,

and the assessment of residual harm to salamander organisms and populations;

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c. Two topical stakeholder advisory committees on the efficacy of (1) options for

stringent conservation measures that would take effect during Extreme Droughts, and

(2) options for the District to promote development and use of alternative water

supplies; and

d. A public/stakeholder advisory committee, in determining the scope of the HCP,

recommending possible avoidance, minimization, and mitigation measures, providing

a forum for public discourse on HCP development and progress, and building

consensus where possible.

Each advisory group met many times during the course of HCP development, and nearly all

meetings, which typically were attended by one or more District directors as well as staff,

were posted as Texas Open Meetings, with publicized agendas and were open to the public

at-large.

• In the latter stages of HCP development and documentation, the District voluntarily

established, used, and intends to continue to use, a standing Management Advisory

Committee (MAC) of experts, stakeholders, and private citizens. The MAC provides

independent initial reviews and annual assessments of the HCP and the progress being

made toward HCP goals, identifies and evaluates additional minimization and mitigation

measures or modifications to existing goals that appear warranted, and makes appropriate

recommendations to the District Board on a periodic basis. This MAC is an integral part

of the District’s continuous improvement process and adaptive management.

The MAC was formed by the Board in February 2013. Its functions are characterized

and its members are identified in Section 6.5.1.2, District Management Advisory

Committee. In effect, the MAC is the continuing advisory vehicle for the previous

advisory groups, and many of the MAC members participated in one or more of those

previous advisory groups during active development of the HCP. In addition to their

prospective involvement in the annual review and reporting process, the District used

MAC members to review and comment on preliminary drafts of the HCP before it was

submitted as part of the ITP application; and continues to use MAC members to help the

District (and the Service) respond to public and agency comments on the HCP and to

ensure that responses address stakeholder and public needs. The MAC meetings are also

posted as Open Meetings to encourage public participation.

4.2 Requested Permit Duration

The proposed ITP for the District would be issued for a term of 20 years and be renewable

thereafter, subject to administrative procedures existent at that time. Local, regional and state water-

resource planning entities in Texas are mandated to use a 50-year time horizon for almost all water-

resource planning functions, ranging from the establishment of DFCs of a groundwater reservoir

managed by a GCD, including the Aquifer, to the regional and statewide water-resource planning

programs of the TWDB. Water-supply strategies are required to supplement the firm-yield supply

available during a recurrence of the DOR within that planning horizon. In the HCP Planning Area,

the DOR is the decade-long drought during 1947–56 (using the District’s drought trigger definitions

discussed in Section 4.1.1.2, Nonexempt Wells and Users). Cleaveland et al. (2011) used tree-ring

73

data and analysis to estimate that a decadal drought like the DOR has a recurrence interval in the

HCP Planning Area of about 100 years. The effects of climate change are just now beginning to be

understood, especially at the regional level, but it is already clear that they may have a profound

impact on drought management imperatives over a shorter period. The effects of climate change

may be particularly important to the habitat of the Covered Species, which suggests the advisability

of a shorter permit term. A term of 20 years represents a rational balance between the factors of

long-term DOR recurrence and likely shorter-term climate change.

The groundwater management plans, regulatory strategies, and tactical measures used by water-

resource management agencies like the District are continuing functions, requiring periodic updating

through the course of long-term planning horizons. As specified in Sections 6.3.2, General

Performance Metrics and Reporting; 6.4, District HCP Adaptive Management Process; and 6.5.1,

[Implementation Responsibility of] Barton Springs/Edwards Aquifer Conservation District, the

measures to be implemented by the District to minimize or mitigate the impacts of take will be

reviewed periodically throughout the term of the ITP and beyond. Because the ITP depends on a

continuing groundwater management program to provide most of the HCP conservation measures, it

is the District’s intent to apply for renewal of an ITP, amended as appropriate, near the end of the

initial term.

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5.0 Analysis of Impacts Likely to Result from Taking

5.1 Covered Species

This HCP proposes incidental take coverage for two endangered species, Barton Springs

salamander (Eurycea sosorum), federally listed as endangered in 1997; and Austin blind

salamander (E. waterlooensis), federally listed as endangered in 2013. Both species are known

primarily from the springs and outlets of the Barton Springs complex of the Edwards Aquifer,

although within recent years occurrences of individuals of the Barton Springs salamander have

been noted at other locations within the Aquifer (further discussed in Section 5.1.2.1, Spatial

Distribution, Barton Springs Salamander). This section describes each species and provides

information on life history, distribution, threats and reasons for decline, and the survival needs

for each species in individual descriptive subsections. Section 5.2, Effects of Take on Covered

Species, assesses taking of these Covered Species by the Covered Activities and its

consequences.

The descriptions that follow draw from several sources compiled by biologists with expertise in

the Covered Species, especially the Barton Springs salamander—its life history, population

characteristics, habitat, and the influences that may cause incidental take. Three of the principal

sources referred to in this section are the Barton Springs Salamander Recovery Plan (Service,

2005); the U.S. Fish & Wildlife Service (Service) final rule that listed the Austin blind

salamander (Service, 2013b); and the COA Barton Springs Pool HCP (City of Austin, 2013).

Citations to the principal and other sources are made where warranted.

5.1.1 Species Descriptions and Life Histories

5.1.1.1 Barton Springs Salamander

The Barton Springs salamander (Figure 5-1) is a member of the Family Plethodontidae (lungless

salamanders). Texas species within the genus Eurycea inhabit springs, spring runs, and water-

bearing karst formations of the Edwards Aquifer (Chippindale et al., 1993). They are aquatic

and neotenic; that is, they retain larval, gill-breathing features throughout their lives and do not

undergo metamorphosis and leave water. Instead, they live in water throughout their life cycle

where they mature and reproduce. The species was first collected from Barton Springs in 1946

(Brown, 1950, Texas Natural History Collection specimens 6317–21) and formally described in

1993 (Chippindale et al.). This species has been a continuing focus of various studies by the

biologists of the COA Watershed Protection Department for more than a dozen years. Studies

have been done both in the field around the spring outlets and in the specialized salamander

laboratory/refugium operated by the COA. Documentation of most of these studies is in the

Barton Springs Pool HCP (City of Austin, 2013).

76

Figure 5-1: (Above) Barton Springs salamander, Eurycea sosorum; (below) Austin blind

salamander, E. waterlooensis. Photo credit: City of Austin, Watershed Protection Dept.

Adults are about 2.5 to 3 inches (63–76 mm) long. The coloration on the adult salamander’s

upper body varies from light to dark brown, purple, reddish brown, yellowish cream, or orange.

The characteristic mottled salt-and-pepper color pattern on the upper body surface is due to

brown or black melanophores (cells containing pigments called melanin) and silvery-white

iridiophores (cells containing pigments called guanine) in the skin. On either side of the base of

the head is a set of three feathery gills that are bright red (Service, 2005).

Juveniles closely resemble adults (Chippindale et al., 1993). Newly hatched larvae are about 0.5

inch (12 mm) long and may lack fully developed limbs or pigment (Chamberlain and O’Donnell,

2003).

77

The Barton Springs salamander is more closely related to the San Marcos salamander than to

either the Austin blind or Texas blind salamanders (Hillis et al., 2001). The Barton Springs

salamander is carnivorous and appears to be an opportunistic predator. Known prey include

ostracods, chironomids, copepods, mayfly larvae, amphipods, oligochaetes, and planarians

(Chippindale et al., 1993; Gillispie, 2011). An analysis of the gastro-intestinal tracts of 18 adult

and juvenile Barton Springs salamanders, and fecal pellets from 11 adult salamanders collected

from Eliza Spring, Barton Springs Pool, and Old Mill Spring most commonly contained

ostracods, amphipods, and chironomids (City of Austin, 2013).

Gravid females, eggs, and larvae of Barton Springs salamander are typically found at different

times of the year in Barton Springs, which suggests that the salamander can reproduce year-

round (Hillis et al., 2001); although generally they are not observed with the same frequency

during drought periods. The eggs hatch in three to four weeks. Hatchlings are about one-half

inch (12 mm) long (snout to tip of tail), often still with yolk sacs and limb buds. Juvenile Barton

Springs salamanders become sexually mature at about 11 months (43–50 mm long) (City of

Austin, 2013). In captivity, Barton Springs salamander has been observed reproducing to an age

of at least eight years (City of Austin, 2013). The representativeness of such characteristics in

the field is not well established.

Observations of courtship among captive pairs of Barton Springs salamanders (Chamberlain and

O’Donnell, 2003) are consistent with Arnold’s (1977) description of the tail-straddling walk,

which is a behavior unique to plethodontid salamanders (Service, 2005). Females of some

salamander species may store sperm for as long as 2.5 years before ovulation and fertilization

occur (Duellman and Treub, 1986). In 2001, a captive Barton Springs salamander female laid

viable eggs one month after being isolated, which indicates that females of this species can store

sperm for at least this length of time (Chamberlain and O’Donnell, 2003).

Since the COA began surveying salamanders in 1993, very few eggs have been found in the

field. The first egg was found detached near a spring orifice in Old Mill Spring in May 2002.

The other three eggs were found near spring orifices in Barton Springs Pool (December 2002,

May and August 2003) (Dee Ann Chamberlain, City of Austin, personal communication, 2003).

It is hypothesized that the Covered Species lay their eggs in the aquifer below the surface

because only a few eggs have been found in the field. Hatching of eggs in captivity has occurred

within 16 to 39 days after eggs have been laid (Chamberlain and O’Donnell, 2003). Hatching

success in captive Barton Springs salamanders may be highly variable as indicated by hatching

rates of 0 to 100 percent that have been reported by the COA (Chamberlain and O’Donnell,

2002, 2003). Egg mortality has been attributed to fungus, hydra (small invertebrates with

stinging tentacles), and other possible factors such as infertility (Service, 2005).

Eggs are laid by female salamanders one at a time and receive no parental care. Although a

female can lay a single egg in minutes, the entire egg-laying event may take several hours,

depending on clutch size (Chamberlain and O’Donnell, 2003). Biologists associated with the

COA captive breeding program have observed clutch sizes ranging from 5 to 39 eggs with an

average of 22 eggs on the basis of 32 clutches (Chamberlain and O’Donnell, City of Austin,

unpublished data, 2003).

78

The first three months following hatching is a critical period for juvenile survival (Chamberlain

and O’Donnell, 2003). Newly hatched larvae have a yolk sac to sustain their nutritional needs in

the early days after hatching. Larvae feeding on prey have been observed 11 and 15 days after

hatching (Lynn Ables, Dallas Aquarium, personal communication, 1999). Although

reproduction has occurred in captivity, it has been sporadic. No consistent methods or

techniques have been found to enhance egg production (Service, 2005).

At times, females have held eggs for more than a year before the eggs are either laid or

reabsorbed. COA biologists believe that stable environmental conditions, water quality,

adequate space, habitat diversity, and food availability may influence egg laying (Chamberlain

and O’Donnell, 2003). Rough surfaces (not smooth like glass) may facilitate successful

spermatophore (sperm mass) deposition and transfer (Service, 2005).

The life span of the Barton Springs salamander in the field is unknown. Assuming that collected

salamanders were at least one year old when collected, reported longevity for individual Barton

Springs salamanders in captivity is at least 15 years (City of Austin, 2013).

Other than gas-bubble trauma (Service, 2005, Section 1.6), only a few physiological anomalies

have been reported in the field for the Barton Springs salamander. They include an infection of

one male adult and possibly one gravid female with immature trematodes (Chamberlain and

O’Donnell, 2002), an unknown myxosporidian parasite, and bacteria in the genera of Aeromonas

and Pseudomonas that have affected salamanders in captivity (Chamberlain and O’Donnell,

2003). It is not known whether these pathogens are present in the spring habitats of the

salamanders or what threat they may pose to salamanders in the field (Service, 2005).

Predation on Barton Springs salamanders in the field is probably minimal when adequate cover

is available for salamanders to hide from predators. Most but not all potential predators of the

salamander that are native to the Barton Springs ecosystem are opportunistic feeders (Service,

2013). Crayfish (Procambarus sp.) and other large predatory invertebrates may prey on

salamanders or salamander larvae and eggs (Gamradt and Kats, 1996). Predatory fish found at

Barton Springs include mosquitofish (Gambusia affiinis), longear sunfish (Lepomis megalotis),

and largemouth bass (Micropterus salmoides). Mexican tetras are non-native fish and are

aggressive generalist predators that are occasionally found in Barton Creek, Barton Springs Pool,

Upper Barton Spring, and Old Mill Spring (Service. 2005). They are reasonably inferred to be

potential predators, but no observations of such predation on the salamander have been reported.

The COA (2013) also reports that the two Eurycea species at Barton Springs may

opportunistically prey on one another.

The sex, age, and number of individuals of the Barton Springs salamander are not precisely

known because the population is believed to be small and the habitat is underwater and from

time to time underground; so some habitat is inaccessible under any circumstances, making a

complete population census impossible. As mentioned, the population size varies more or less

repetitively but not regularly, typically in response to natural variations in resources and

environmental conditions. Over the long term, statistical trends can be inferred from the

exhaustive and extensive surveys and censuses of observable individuals that are being

conducted by the COA, in association with recorded variations in climate, springflow, DO

concentration, and other relevant factors that influence habitat (City of Austin, 2017a, 2013,

2007b).

79

5.1.1.2 Austin Blind Salamander

The Austin blind salamander was formally described by Hillis et al. (2001). The Service

provides a comprehensive description of this species and its ecological requirements in its recent

listing rule (Service, 2013b), which is incorporated by reference into this section.

The Austin blind salamander (Figure 5-1) is also a member of the Family Plethodontidae

(lungless salamanders), one of the several Texas species within the genus Eurycea that inhabit

springs, spring runs, and water-bearing karst formations of the Edwards Aquifer (Chippindale et

al., 1993). It is closely related to the Texas blind salamander (Eurycea [formerly Typhlomolge]

rathbuni), which is found in the San Antonio segment of the Edwards Aquifer in San Marcos

(Hillis et al,. 2001).

The Austin blind salamander averages about 2 inches (51 mm) long (EARIP HCP, 2012),

slightly smaller than the Barton Springs salamander. Other physical characteristics that

distinguish the Austin blind salamander from the Barton Springs salamander include eyespots

covered by skin instead of image-forming lenses, an extended snout, fewer costal (upper body)

grooves, and pale to dark lavender coloration (Hillis et al., 2001). In June 2001, the Austin blind

salamander was designated a candidate for listing as endangered or threatened (Service, 2005).

The species was listed as endangered on August 20, 2013 (Service, 2013b).

The Austin blind salamander is also carnivorous and appears to be an opportunistic predator.

There is evidence of partial overlap in diet composition and egg deposition sites of the Covered

Species, which has been interpreted as indicative of natural selection for ecological niche-

partitioning (different patterns of resource use) to reduce competition (Vrijenhoek, 1979; Pianka,

2000). Austin blind salamander is believed to feed mostly on blind amphipods and isopods

found within the aquifer; but when they are at the surface of the springs, they also will consume

other small invertebrates (City of Austin, 2013). These factors can maintain genetic divergence

between the Covered Species (Paterson, 1985).

The uncertainties and limitations of surveying to determine the sex, age, and number of

individuals of the Austin blind salamander are not precisely known because the population is

believed to be small and the dominant habitat is subterranean (underground) and aquatic (Hillis

et al., 2001). So most of its habitat is inaccessible under any circumstances, which makes

surveying of the species unreliable. Accordingly, less is known about the sex, age, and number

of individuals—and therefore life-cycle characteristics—for Austin blind salamander than for

Barton Springs salamander.

5.1.2 Species Distribution


Both species are observed in the vicinity of the spring outlets, although the epigean Barton

Springs salamander is more likely to be found at and near submerged rock ledges and gravelly

areas. After the COA completes the spring-run restoration (part of the Eliza Springs Daylighting

Project) described in the Barton Springs Pool HCP (City of Austin, 2013), the re-aerated water of

the spring run typically will have larger DO concentration than that of the water issuing from the

outlets, especially during low-flow conditions. This is important, in that some researchers (for

80

example, Turner, 2007) have suggested the salamanders appear to be able to migrate locally to

areas of less stress (higher flow, higher water velocity, larger DO concentration, more prey,

fewer predators) in the Aquifer and in spring runs during periods of even moderate drought. No

Critical Habitat has been designated by the Service for the Barton Springs salamander.

Individual salamanders that appeared to be morphologically identical to Barton Springs

salamander had previously been observed at several locations remote from Barton Springs, but

those were not confirmed by genetic information to be Barton Springs salamander until fairly

recently. In mid-2015, an individual salamander that has very similar if not identical morphology

to the Barton Springs salamander was unexpectedly collected by endangered-species biologists

from a 200-foot deep monitor well in the Aquifer at the offices of Zara Environmental LLC,

more than nine miles from Barton Springs (Zara Environmental, 2015). This well is in the

transition zone of the Aquifer, with the wellhead located in the confined zone but near its

hydrologic boundary with the recharge zone. Its discovery and subsequent confirmation

reinforced an emerging consensus among salamander biologists that significant habitat of the

Barton Springs salamander exists within the Aquifer remotely from the Barton Springs complex.

More recently, individual salamanders identified as Barton Springs salamander have now been

documented at three other Aquifer locations even more distant from the Barton Springs outlets

(City of Austin, 2017a). In addition to springs and seeps in the Aquifer, more recently individual

salamanders identified as Barton Springs salamander have been documented at springs issuing

from the Trinity Aquifer beyond the District boundaries (Devitt and Nissen, 2018).

While it is not currently known whether these newer locations represent habitat of a robust

additional population or simply migratory members of the same population at Barton Springs,

their occurrence documents the likely habitat of this Covered Species at location(s) remote from

the Barton Springs complex, designated in this HCP as the “far-field” habitat. One of the far-

field locations is Blowing Sink Cave, which has allowed entry into the Aquifer for salamander

counting and far-field habitat characterization (see Section 3.2.2.2.1, Overview of Habitat

Characteristics and Supported Populations).

The size and significance of the population(s) suggested by these other occurrences, especially as

they relate to the evolutionary path and subsurface migration of these non-troglobite (living

entirely within the dark zone of caves) species, perhaps facilitated by the better oxygenated

interface at the water table, are currently unknown and deserve further investigation. But after

discussion with the Service, the District has been encouraged to consider these remote locations,

even though very poorly characterized currently, as additional known habitat of the Barton

Springs salamander in the District HCP, rather than to be addressed as a potential Changed

Circumstance.

All of these far-field locations within the Edwards Aquifer but remote from the Barton Springs

complex are within the currently proposed ITP Area.


The Austin blind salamander is sympatric with (occurs in the same or substantially overlapping

range with) the Barton Springs salamander, probably incidentally in the epigean environment on

the basis of its morphology (form and structure). The Critical Habitat for Austin blind

81

salamander, as designated by the Service (2013b), is shown in Figure 5-2. Its range away from

the spring outlets is in the subsurface, within the Aquifer, and is largely inferred from ranges

reported for other similar species (Service, 2013b). Its presence and migration away from the

spring outlets are implied by the Critical Habitat designation to contribute to assuring the

redundancy, representation, and resilience of the Austin blind salamander (Service, 2013a).

Hillis et al. (2001) also notes its ability to migrate locally to areas of reduced stress, as does the

Barton Springs salamander. However, currently no data suggest how far afield within the

Critical Habitat Area, in the subterranean region away from the outlets, the organisms migrate or

have migrated. Unlike Barton Springs salamander, Austin blind salamander has not been

regularly observed at the non-perennial Upper Barton Spring, and has not been documented at

any location remote from the Barton Springs complex. The hydrogeologic setting suggests the

subterranean habitat near the outlets is a complex, three-dimensional network of solution-

enlarged openings; and because Barton Springs complex flow issues from both confined and

unconfined parts of the Aquifer (Hauwert et al., 2004), different DO characteristics likely exist in

the nearby subterranean environment (Lazo-Herencia et al., 2011). Although both species have

been observed in the vicinity of the spring outlets (other than Upper Barton for Austin blind

salamander), between the outlets, and in dissolution cavities in the rocks underlying the outlets,

Austin blind salamander is more likely to be in the subterranean parts of and between the outlets

and in the dissolution cavities in the rocks underlying spring runs.

5.1.3 Reasons for Decline and Threats to Survival

The Service recently issued its final rulemaking on the Austin blind salamander (78 FR 51278),

which contains a comprehensive compendium of current information on, analysis of stresses on,

and threats to this species (Service, 2013b). Such a comprehensive assessment was not made in

the earlier listing process for Barton Springs salamander, but similar factors were identified and

addressed in its Recovery Plan (Service, 2005).

In its listing rule, the Service has identified a relatively large number of specific stressors that

adversely affect the Covered Species and that, either singly, in combination, or cumulatively

over time, are reasons for decline and threats to survival of these species (Service, 2013b).

These stressors are summarized in Table 5-1, which also provides an indication of the District’s

ability (legal authority, regulatory purview, financial means) to take actions that affect each of

the stressors and thereby contribute to responding to those threats. The District’s Covered

Activities do not relate to most of these threat stressors. They are included here primarily as an

indication of the overall risks to the ecosystem of the Covered Species.

The primary threat for the Covered Species is believed to be the present and threatened

degradation of the habitat by reduced water quality and quantity at the surface, in the subsurface,

or both, and also by the physical disturbance of the surface habitat of spring sites (Service,

2013b). The Service has determined that in aggregate the threats identified are both imminent

and high in impact on the Covered Species. For example, in its most recent listing rule

documentation, the Service concludes that “…the Austin blind salamander is in danger of

extinction now throughout all of its range…” and goes on to explain that this finding “…is based

on our conclusions that this species has only one known population that occurs…in Barton

Springs. The habitat of this population has experienced impacts from threats, and these threats

82

Figure 5-2: Service-designated Critical Habitat for the Austin blind salamander. Designated Critical Habitat has both surface and subsurface components. All of the surface habitat and most of the

subsurface habitat, totaling about 120 acres (48.6 hectares), are within the City of Austin’s Zilker Park and protected

from future development. Source: Service, 2013a.

83

are expected to increase in the future. We find that the [species] is at an elevated risk of

extinction now, and no data indicate that the situation will improve without significant additional

conservation intervention” (Service, 2013b). Although this specific determination addresses the

Austin blind salamander, which was just recently listed, the same threats and stressors exist for

the Barton Springs salamander population; and that species is considered equally at risk for

exactly the same reasons and in need of conservation to reduce the risk of extinction.

But as Table 5-1 also indicates, most of the stressors and circumstances that harm the two

species are beyond the District’s ability and authority to affect, avoid, ameliorate, minimize, or

mitigate. Only those reasons for decline and threats to the survival of the Covered Species that

the District’s activities affect in either a positive or negative sense are addressed further in this

section of the HCP. The District HCP’s Covered Activities relate solely to managed

groundwater withdrawals from the Aquifer under its integrated drought management program.

Managed withdrawals directly affect only the amount of groundwater that issues from the spring

outlets. This is because water not withdrawn from wells discharges at spring outlets, generally

on an equivalent-volume basis during drought conditions (Smith and Hunt, 2004). In turn, as

described in Section 3.2.2.2 Ecological Setting, the DO concentration, representing the amount

of oxygen dissolved in the water forming the springflow, decreases as the amount of water

discharging from the Aquifer as springflow decreases (Herrington and Hiers, 2010), and TDS

concentration, representing the amount of dissolved solids (“salts”) in springflow, increases as

the springflow decreases. The concentration of dissolved solids increases because older, more

saline water constitutes a larger proportion of low springflow than high springflow (Johns,

2006). These changes in water chemistry are affected indirectly by the District’s groundwater

management program, which in turn affects the amount of take of the Covered Species.


The threats to and stressors of the Barton Springs salamander that are addressable by District

actions and decisions and that potentially relate to the existence and amount of take and therefore

its impact are the following (Service, 2013b):

1. Reduced springflow at the Barton Springs outlets during severe (Stage III Critical and

Stage IV Exceptional) droughts, a type of stochastic (random, with a probability of

occurrence/recurrence) event on which groundwater withdrawals are superimposed;

2. Decreased DO concentration in springflow during severe drought; and

3. Somewhat higher ionic constituent concentrations (as expressed by specific conductance)

in springflow during severe drought.

The Service’s Barton Springs Salamander Recovery Plan includes an examination of the various

cultural/anthropogenic threats and stresses and recommends guidelines and action steps and an

implementation program to minimize or avoid them as integral elements of the recovery

measures (Service 2005). This District HCP is a complement to the Barton Springs Salamander

Recovery Plan with respect to minimizing groundwater withdrawals during drought. Because

natural processes such as supersaturation of dissolved gases in the salamander’s body have

84

occurred in the past and may pose continuing threats to the salamander (City of Austin, 2013;

Service, 2005; 2013a), they may also bear on the feasibility and effectiveness of potential

conservation measures for this HCP.


The same factors identified and observations made for the Barton Springs salamander are also

pertinent to the Austin blind salamander. This is especially true for those aspects of habitat

change that can be affected by the District’s Covered Activities; that is, the quantity and resultant

water chemistry of springflow during severe drought that result in take and its impact:

1. Reduced springflow at the Barton Springs outlets during severe (Stage III Critical and

Stage IV Exceptional) droughts, a type of stochastic (random, with a probability of

occurrence/recurrence) event on which groundwater withdrawals are superimposed;

2. Decreased DO concentration in springflow during severe drought; and

3. Somewhat higher ionic constituent concentrations (as expressed by specific conductance)

in springflow during severe drought.

85

Table 5-1: Summary of threats to Covered Species

Adapted from: Federal Register, vol. 78, no. 161, p. 51278 and the following.

Threat Factor Ecological Impact Source of

Concern Adverse Effects

Affected by

District?15

Stressor A

Present or

threatened

destruction,

modification, or

curtailment of its

habitat or range

Water Quality Degradation Urbanization

Increased impervious cover and

chronic degradation of stream

hydrology and contamination of

aquatic habitat from expansion of

roadways, residential, commercial

and industrial development

No

Increased magnitude and frequency

of high flows and flashiness that

disrupts biotic communities No

Changes in stream morphology and

water chemistry, including increased

contamination and toxicity No

Negative effects on prey base No

Increased sedimentation that covers

graveled habitat No

15 Refers to effects of direct District actions within its authority as a GCD

86



Affected by

District?15

Hazardous Materials

Spills and Releases

Highway-transport accidents may

release gasoline, chemicals, heavy

metals like lead and arsenic, oil and

grease, and toxic petroleum

hydrocarbons to streams and then the

Aquifer

No

Releases of toxic organics and

hydrocarbons from breaks in oil and

gas pipelines and related facilities No

Stressor A

(continued) Water Quality Degradation

(continued)

Hazardous Materials

Spills and Releases

(continued)

Leaking underground storage tanks

that release gasoline and

petrochemicals to the Aquifer No

Breaks and overflows in conveyance

lines and failures of treatment

facilities for water and sewage that

introduce a panoply of contaminants

to streams and the Aquifer

No

Construction

Activities

Siltation and increased sediment and

chemical loads from excavations for

roads, tunnels, pipelines, and shafts No

Siltation and increased sediment and

chemical loads from excavation and

operation of quarries and gravel pits No

Disruption of hydrologic pathways

from excavations (although none are

known or likely for these species) No

87



Affected by

District?15

Introduced Specific

Contaminants and

Pollutants

Acute and chronic toxicity to

Covered Species and prey, through

sediment or water No

Adverse effect on eggs and larvae No

Impaired reproduction, growth, and

development of life cycle

requirements No

Adverse effect on prey species

availability No

Morphological deformities No

Altered capability for feeding,

moving, and reproduction: loss of

survivability No

Nutrient enrichment and subsequent

changes in trophic state (indicator of

amount of living material [usually

algae] supported) and biological

growth- and decomposition-related

oxygen availability problems

No

Stressor A

(continued) Water Quality Degradation

( continued) Changes in Water

Chemistry

Specific conductance may indicate

other pollutants as well as elevated

ionic stress No

Salinity and its specific ions can alter

the internal water balance and create

mortality in various species,

including prey species

Yes

88



Affected by

District?15

Dissolved oxygen depression reduces

respiratory efficiency, metabolic

energy, and reproduction rates, and

ultimately survival

Yes

Water Quantity

Degradation

Urbanization

Change in magnitude, frequency, and

duration of runoff reduces base flow

of recharge streams and concomitant

decrease in aquatic community

diversity

No

Increased storm runoff increases

erosion and sedimentation and more

easily flushes larvae from materials

on which it lives

No

Reduction in infiltration increases

flashy runoff, reduces recharge and

therefore decreases springflow No

Natural Drought

Reduced springflow is associated

with lower dissolved oxygen

concentration, lower water velocities,

higher salinity, higher temperature

variations, and increased

sedimentation of habitat, all of which

adversely affect the Covered Species

and availability of their prey

No

89



Affected by

District?15

Stressor A (cont'd)

Water Quantity

Degradation (continued)

Climate Change

Increased drought intensity and

duration and higher average

temperatures leads to more water

demand, larger temperature

variations, less recharge, smaller

springflow, and more saline

intrusion, all of which adversely

affect the Covered Species and

availability of their prey

No

Increased Well Use

Reduced spring flow may cause

stranding and interference with

feeding/predation, as well as

somewhat reduced dissolved oxygen

and slightly higher salinity

Yes

Physical Modification of

Surface Habitat Modification of

Existing Habitat

Flooding may alter surface material

and channel morphology, adversely

affect protective vegetation, and

flush individuals from their habitat

No

Sedimentation mobilizes silt and clay

that are suspended in water and make

water turbid, which impairs breathing

because of clogged gills and reduces

ability to locate food or avoid

predators

No

90



Affected by

District?15

Sedimentation mobilizes sediments

and associated contaminants that are

then re-deposited and cover/fill

surfaces necessary for life activities.

No

Stressor A

(continued)

Physical Modification of

Surface Habitat

(continued)

Modification of

Existing Habitat

(continued)

Impoundments alter stream

morphology, and flow patterns that

allow increased siltation and support

larger predators.

No

Other human activities, including

frequent human visitation and

vandalism, result in habitat

disturbance/destruction and loss of

cover available for breeding, feeding,

and sheltering of Covered Species

No

Stressor B:

Overuse for

commercial,

recreational,

scientific, or

educational

purposes

Reduction in population

size Significant population

declines

Over-collection for scientific

purposes could negatively impact the

species in combination with other

threats; not considered a serious

threat at this time

No

91



Affected by

District?15

Stressor C:

Disease or

predation

Reduction in population

size Not considered a

threat No problems observed; not

considered a threat to population N/A

Stressor D:

Inadequacy of

existing regulatory

mechanisms

Past, current, and future

impacts to species as noted

above

Inability to prevent

further impacts to

species in the future

Federal and state laws have not

sufficiently prevented such impacts No

Local laws, regulations, and

ordinances are not sufficient to

prevent such impacts No

Groundwater Conservation District

regulations are not sufficient to

prevent such impacts Yes

Stressor E:

Other natural or

man-made

stressors affecting

continued

existence of the

species

Synergistic and additive

adverse interactions among

stressors

Result of random

events on very small

population

Severe drought, abetted by

groundwater withdrawals, may

reduce quantity and change

chemistry of springflow, which

exacerbate other impacts on species,

especially as re-colonization is not

probable

Yes

92



Affected by

District?15

Catastrophic contaminant spills or

leaks of harmful substances that

exacerbate other impacts on species No

Other natural factors

Ultraviolet-B radiation may

exacerbate other impacts No

The highly restricted range (one

location) and the entirely aquatic

environment make the Covered

Species highly vulnerable to random

events such as catastrophic spills,

storms , and severe droughts that

could eliminate the species

No

93

5.1.4 Survival Needs Affected by Covered Activities

Both the Barton Springs salamander and the Austin blind salamander are believed to have very

similar needs to ensure their survival. At present, there are insufficient data and information to

distinguish major differences between the species in this regard. Accordingly, the discussion in

this section applies to both species.

Chief among their survival needs, as inferred from their sole habitat characteristics discussed in

Section 5.1.1, Species Descriptions and Life Histories; and 5.1.2, Species Distribution, are the

following:

1. A supply of high-quality freshwater with a relatively narrow range of physiochemical

conditions of pH, alkalinity, and water temperature: These conditions are met by

groundwater continuously discharging from a non-polluted karst aquifer (City of Austin,

2013; Service, 2013b);

2. Sufficient DO flux (volume per unit area per unit time), representing a combination of DO

concentration and water velocity past the highly adapted salamander gill structures: The

minimum flux required is unknown (Poteet and Woods, 2007; Mahler and Bourgeais, 2013);

3. Water with concentrations of ionic constituents (expressed as TDS concentration) that are

sufficiently low such that the water supports the egg and larval life stages of the salamander

(Service, 2013b): The threshold TDS concentration in springflow beneath which egg and

larval life stages are supported is unknown, but it is believed to be high enough that minor

increases in TDS concentration associated with saline water intrusion during severe drought

do not affect egg and larval life stages;

4. Interconnected, submerged surface and subsurface habitat for various life activities and from

time to time for protection: Given the morphological differences, the Austin blind

salamander uses the submerged subsurface environment mostly, whereas the Barton Springs

salamander uses the submerged surface and near-surface environment more. The

interconnection between the submerged surface and near-surface environments may be

critically important to both species for providing food and avoiding predation (Service,

2013b); and

5. Given the small size of both populations and the lack of redundancy for each, the

population’s persistence (survivability) in the face of environmental and demographic

challenges depends on the number, duration, frequency, and magnitude (size of reduction) of

low springflow events at the spring outlets during severe droughts not exceeding the

resiliency of the species (Service, 2013b).

These survival needs and life history requirements are characterized in more detail by the Service

(2013b).

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The District’s Covered Activities and conservation program affect and address the first, second,

and third of these needs, at least indirectly, and its drought management program is intended to

reduce incrementally the magnitude of low springflow events that could affect the persistence of

the population (the fifth need above). In the following section, the take by the Covered

Activities is characterized and quantified, and then the impacts of take on the populations are

described.

5.2 Effects of Take on Covered Species

The assessment presented in Sections 5.1.3, Reasons for Decline and Threats to Survival, and

5.1.4, Survival Needs Affected by Covered Activities, strongly suggests that the scientific basis

and factors for considering take by the Covered Activities are essentially the same for both

Austin blind salamander and Barton Springs salamander, differing primarily in amount of

supporting information available. The COA's Barton Springs Pool HCP (City of Austin, 2013)

does not distinguish differences in the effectiveness of protections afforded by its conservation

measures between the two species. Further, substantially more information than is now known

on the habitat requirements and life histories of both species, but especially Austin blind

salamander, and their response to stressors, would be needed to propose and assess differential

requirements between the two species.

The unavoidable effects of the District’s Covered Activities are also not able to be differentiated

between effects on one of these species and not the other. Therefore, the effects on the species

are addressed together in this section. However, potential differential impacts, that is,

consequential results of take on each of the species populations, are addressed in Section 5.3,

Impact of Take on Covered Species Populations. An important operational premise of this HCP

is that the measures to be adopted for the conservation of Barton Springs salamander will not

substantially harm Austin blind salamander and its habitat, and vice versa. The current state of

knowledge appears to provide no compelling basis to refute this premise. In particular, there is

no known difference in the sensitivity to DO concentrations and salinity between the two

species, and while opportunistic predation may occur between the species, neither is known to be

dominant in this regard (City of Austin, 2013).

Accordingly, in this section of the HCP addressing the effect of take, unless otherwise specified,

the term “Covered Species” refers to both of the species and their attributes.

5.2.1 Experimental Assessment of Salamander Responses to

Changes in Water Chemistry Related to Springflow

DO concentration and specific conductance have been identified as potentially significant

parameters to be investigated during the course of the District HCP to understand the levels of

stress on and mortality of both salamanders (for example, Turner, 2004b). Before the HCP was

begun, no scientific study of the physiological responses of either Covered Species to changes in

these parameters was known. Accordingly, a pioneering multistage laboratory study was

commissioned and funded by the District as part of the HCP development process to inform the

assessment of changes in water chemistry on the Covered Species. The research was done by

investigators at The University of Texas at Austin, Section of Integrative Biology, and later

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supplemented by researchers at Baylor University’s Department of Environmental Science. In

the first stage of the work, the investigators evaluated stressor-response relationships and

sensitivities important to conservation on Barton Springs salamander and a surrogate species

across a range of DO concentrations and specific conductance (Poteet and Woods, 2007).

Approaches that identify stressor-response thresholds (DO concentrations below which, and

specific conductance above which, likely harm salamanders) are valuable for supporting

environmental management decisions (Suter, 2006). The work with specific conductance

showed no appreciable response by a surrogate (for the Covered Species) salamander to specific

conductance several multiples higher than those in Barton Springs flow. Those findings are

discussed below at the beginning of Section 5.2.1.2, Stressor-Response Study Findings and

Applications. On that basis, the investigators, with the District’s concurrence, discontinued

further analysis of response to specific conductance variations and focused exclusively on

analysis of response to DO concentration variations. Thus, the stressor-response experiments for

the District HCP were designed to determine hazards to individuals from just one of the stressors

(DO) of the Covered Species. Although Covered Species are susceptible to cumulative risks

from a variety of natural and anthropogenic stressors (Table 5-1), stress from incidental DO

concentration variability is considered the primary stressor to which the District’s Covered

Activities contribute. This approach (focusing on the primary stressor) is preferred when

considering threatened and endangered species for which an adverse impact on individuals of the

population can be significant (Suter, 2006).

The first-stage study documented in the report by Poteet and Woods (2007) was subsequently

enhanced with further investigation, computations, and analysis as part of the HCP, using a

Probabilistic Ecological Hazard Assessment (PEHA) approach to relate the laboratory study

findings to threshold responses of salamanders to DO concentrations in spring habitats for the

first time. This second-stage study, which involved a closely related salamander species as a

surrogate for the Covered Species and historical data, provided a unique contribution to

understanding DO stress to an endangered species. The enhanced study report was subjected to

considerable peer review before being published in Copeia, the journal of the American Society

of Ichthyologists and Herpetologists (Woods et al., 2010). The report is included in its entirety

as Appendix I. The HCP relies heavily on the conclusions in the published report, but data in the

original report (Poteet and Woods, 2007) are also instructive.

5.2.1.1 Laboratory Study Design

The investigators selected and used a closely related salamander species, the San Marcos

salamander (Eurycea nana), as a surrogate for the Covered Species because its genetics and life

history are similar to those of the Barton Springs salamander (Chippindale et al., 2000). San

Marcos salamander occupies similar karst-fed springs in Central Texas, and the two species have

similar physiologies. Both species are federally protected, but the captive population size of San

Marcos salamander is considerably larger than that of Barton Springs salamander and especially

Austin blind salamander (Poteet and Woods, 2007). On the basis of metabolic tests on both

species to evaluate response to changes in DO concentration and specific conductance (Poteet

and Woods, 2007), San Marcos salamander appeared to respond similarly to the Barton Springs

salamander under a variety of test conditions. The ready, nearby availability of a surrogate

species that was so similar to the Covered Species was fortuitous and exceptionally rare for

stressor-response studies with endangered amphibians (Woods et al., 2010).

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Woods et al. (2010) used the testing procedure of Poteet and Woods (2007) (Figure 5-3) to

generate mortality estimates after 28 days of exposure to various DO treatment levels under

controlled laboratory conditions. In addition, Woods et al. did a 60-day study on juvenile San

Marcos salamander, exposing individuals to various DO concentrations to provide data on sub-

lethal effects such as metabolic rate variation, growth rate, and behavioral response. Survival

and sub-lethal growth measurements are routinely used in ecological hazard assessments because

these response variables are highly relevant for population sustainability of threatened and

endangered species (Suter, 2006).

Figure 5-3: Example setups for studying salamander response to stressors . Representation of two laboratory experimental setups to measure salamander response to stressors in the study of

Poteet and Woods (2007). Image on left is for 28-day stressor-response study, and image on right is for metabolic

rate study. (Photo courtesy of M. Poteet and A. Woods).

5.2.1.2 Stressor-Response Study Findings and Applications

One of the primary findings of the Poteet and Woods (2007) study was that increases in specific

conductance do not result in salamander mortality, even increases to very high specific

conductance. This finding is the result of what appears to be the only laboratory study available

for the species of concern. The finding is not surprising, particularly for organisms that have

adapted to natural habitat changes in the past. However, the finding relates only to adult and

juvenile salamanders. Others have suggested that increased salinity could have adverse

consequences on the egg and larval stages of the salamander (Service, 2013b). No empirical

studies of this latter possibility have been documented. But given the relatively small increase in

TDS concentrations (from about 400 mg/L to less than 500 mg/L) associated with low

springflow (Herrington and Hiers, 2010) and the adaptation of Covered Species populations to

low springflow, any adverse effect on the Covered Species is likely negligible. The Covered

Species are exposed to similar and even larger salinity variations on a recurring basis during

high-flow periods, although the durations of such periods are over much shorter time intervals

than those of severe drought. Accordingly, salinity was not considered by the investigators to be

nearly as important a factor as DO concentration in affecting habitat quality for purposes of

biological evaluation in the District HCP. The narrative that follows thus focuses only on DO.

Although many natural and anthropogenic chemical constituents that may occur in groundwater

could adversely affect the Covered Species, the District’s Covered Activities only affect the

concentration of those few natural constituents that are specifically related to springflow. In this

regard, only DO concentration is judged to be a quantitative indicator of take of the Covered

Species in the meaning of the Act.

97

In the 28-day adult stressor-response study, groups of salamanders were exposed to

progressively larger DO concentrations: 1.3, 2.4, 3.6, 4.6, and 7.5 mg/L, each in individual

aquariums. Figure 5-4 shows a response curve to the DO exposure concentrations. Mortality

fell abruptly between about 2 and 4 mg/L. Some salamander mortality occurred within 28-days

in each of the three lowest treatments (1.3, 2.4, and 3.6 mg/L), and there was 100% mortality

within 48 hours in the two lowest treatments; no DO-related mortality was observed in either of

the two highest treatments (4.6 and 7.5 mg/L).

Figure 5-4: Relationship between mortality of San Marcos salamander and five exposure

concentrations of dissolved oxygen in a laboratory study. Source: Woods et al. (2010).

Lethal Concentrations (LCx) are estimated concentrations of an environmental parameter at

which level a certain animal or organism has a given likelihood (percent chance) of dying in a

given amount of time, under constant, controlled conditions. In other words, LCx is the exposure

concentration (level) in which x% of the organisms die. Woods et al. estimated a series of LCx

values of DO for the Barton Springs salamander—the DO concentrations that would presumably

cause 5%, 10%, 25% and 50% mortality for adult San Marcos salamander individuals if exposed

continuously over a 28-day period (Table 5-2; Woods et al., 2010):

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Table 5-2: Summary Lethal Concentrations and Dissolved Oxygen Concentration (Woods et al.,

2010). The +/- values represent the 95% confidence interval (see next Section 5.2.1.3, Implications and Limitations of the

Stressor-Response Study).

Lethal Concentrations

(LCx) Dissolved Oxygen

Concentration (mg/L)

LC5 4.5 ±0.5

LC10 4.2 ±0.3

LC25 3.7 ±0.1

LC50 3.4 ±0.2

These concentrations represent DO stressor-response thresholds for San Marcos salamander, a

reasonable surrogate species for the Barton Springs salamander and, for this HCP, also Austin

blind salamander. In particular, the LC50 and the LC5 may provide useful benchmarks for

estimating the quantity of take and negligible ecological risk that is likely to occur under the

anticipated springflow conditions of the HCP. For example, the concentration of DO at LC50

(causing 50% chance of mortality after 28 days of exposure) is about 3.4 mg/L, which, if it

occurred for a continuous 28-day period or longer in one of the springs, would pose a grave

threat to salamander survival. On the other hand, DO levels at or above LC5, 4.5 mg/L, showed

no observable effects in any experiment (Woods et al., 2010), so little threat to salamander

survival would be inferred. During prolonged, severe droughts, the DO concentrations typically

range non-linearly between these two DO levels (Woods et al., 2010).

In this regard, other researchers have also noted that the Barton Springs salamander seems to be

adapted to waters that are variably under-saturated with respect to DO (Turner, 2007), which

indicates some resiliency of the salamander to DO variations.

The stressor-response study also yielded the No Observed Adverse Effect Level (NOAEL)

threshold DO levels for juvenile as well as adult San Marcos salamanders. Juvenile growth rate

studies were done over a 60-day period to determine the effects of exposure to various DO levels

on metabolic activity and growth. The lowest DO concentration for the 60-day juvenile growth

study was 4.4 mg/L.

The results of the 60-day analysis are shown in Table 5-3. Although juveniles in the lowest DO

exposure concentration (4.4 mg/L) had growth rates that were approximately 30% lower than

control salamanders, the growth rates were positive and were not significantly different than

those of the controls (Woods et al., 2010). Uncertainties exist, but based on these unique

laboratory studies, salamanders exposed to DO concentrations at or higher than 4.4 mg/L are not

99

expected to be adversely affected.16 For purposes of this HCP, the NOAEL for all forms of the

Covered Species is considered 4.5 mg/L DO. However, to be conservative in this HCP, the

District ultimately selected to use combined springflows associated with a DO level of 5.0 mg/L

as the threshold for the onset of DO-related behavioral effects, constituting take. This higher DO

concentration is the same as that identified by the Service as the recommended water quality

criterion applicable to threatened and endangered species in karst groundwater in the Aquifer,

specifically the Barton Springs salamander (White et al., 2006)

Table 5-3: Summary of growth rates of juvenile San Marcos salamander over 60 days in different

dissolved oxygen concentrations. Source: Woods et al. (2010).

Treatment

Dissolved Oxygen (mg/L) Number

Growth Rate (mg/day)

1 4.44 5 0.15 2 5.17 4 0.33 3 5.31 4 0.26 4 6.35 5 0.24 5 8.22 4 0.23

The PEHA used by Woods et al. is based on USGS datasets of DO concentration and springflow

representing 30 years of record. The procedures used were uniform across the datasets, which

was a major criterion for the PEHA investigation. In those datasets were very few observations

of DO concentration at low flows or values below 4.5 mg/L. The DO dataset for the primary

outlet at Main Springs contained more of these observations than datasets for other outlets; but

there were only 27 observed springflow-DO concentration pairs in which springflow was less

than 20 cfs (0.57 m3/s) in that dataset, and only 35 DO concentration observations less than 4.5

mg/L. The mean of the 27 DO concentrations paired with springflows less than 20 cfs is 4.69

mg/L. No statistically significant relationship was observed between flows below 20 cfs and

associated DO levels. This result imposes some limitation on the general applicability of the

findings and their comparability with findings from datasets collected later for other outlets.

16 Some reviewers of early drafts of this HCP noted that a higher standard, specifically the 5.0 mg/L DO criteria for

lentic (still water) systems should be used, in keeping with existing surface water quality standards and/or for

providing a safety margin. This is not a comparable standard and is used for different purposes. The surface water

quality standard is intended to provide a general condition that would support a diversity of aquatic life under all

ambient conditions in lakes and reservoirs with other constituents and is applied only outside a mixing zone. In any

event, it is not applicable to springflow per se or spring-fed pools. Further, it is not intended to be equivalent to a

NOAEL for any specific aquatic species, nor is it designed to be used as a threshold for assessing take. Sound

environmental management incorporates margins of safety in actual enforceable standards whenever feasible to

accommodate cumulative effects of all constituents. But standards that have such safety margins do not indicate

when physiological and/or behavioral effects for a given species are evident, including in particular these Covered

Species. Woods et al. (2010) assert that the typical 5.0 mg/L DO surface water quality criteria, if it were applicable,

would likely be protective of the Barton Springs salamander; but those researchers did not suggest that it should be

the NOAEL. .

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The PEHA was used to estimate the likelihood (percent chance) that DO concentrations in

springflow at Main Springs, Eliza Spring, and Old Mill Spring would be at or below response

thresholds for San Marcos salamander. A likelihood estimate can also be called a

nonexceedance probability and can refer to the percentage of time a concentration is at or below

a response threshold.

Table 5-4: Likelihood (percent chance) that DO concentrations in springflow at Main Springs,

Eliza Spring, and Old Mill Spring would be at or below response thresholds for San Marcos

salamander. Response thresholds (LCx) are DO concentrations that cause mortality in 5, 10, 25, and 50% of adult San Marcos

salamander after 28 days of exposure, and the No Observed Adverse Effect Level (NOAEL) for juvenile San

Marcos salamander growth following a 60-day study. The +/- values represent the 95% confidence interval (see next

Section 5.2.1.3, Implications and Limitations of the Stressor-Response Study). Source: Woods et al. (2010).

Response Threshold

(LCx) Length

of Study

Response Threshold DO Conc. (mg/L)

Probability of Nonexceedance (Percent chance DO conc. at or below

response threshold conc.)

Main

Springs Eliza

Spring Old Mill Spring

LC5 28-day 4.5 +/- 0.5 5.2 6.8 30

LC10 28-day 4.2 +/- 0.3 2.3 3.024 --

LC25 28-day 3.7 +/- 0.1 0.4 0.4 15

LC50 28-day 3.4 +/- 0.2 0.08 0.1 11 NOAEL 60-day 4.4 4.5 5.8 28

Table 5-4 data indicate, for example, that the probability that the DO concentration in flow at

Main Springs would be less than the concentration at or below which 5 percent of the

salamanders would be expected to die after 28 days of exposure (about 4.5 mg/L) is 5.2%. Or

briefly, the probability of a DO concentration at Main Springs not exceeding about 4.5 mg/L is

5.2%. Similarly, for Eliza Spring, the nonexceedance probability for the same response threshold

is 6.8%; and for Old Mill Spring, 30%. At the other end of the mortality spectrum, Table 5-3

data indicate that the LC50 concentration (about 3.4 mg/L), the level at which 50% mortality of

salamanders would be expected after 28 days of exposure, has a likelihood of occurring 0.1% of

the time, or less, for Main Springs and Eliza Spring. The probability of nonexceedance of the

NOAEL for Main Springs is 4.5%, and for Eliza Spring, 5.8%. Thus, there is a 4.5 % likelihood

of a DO concentration not expected to adversely affect juvenile salamander growth (4.4 mg/L) at

Main Springs. Nonexceedance probabilities for Old Mill Spring were substantially higher than

those for the other two springs.

Results from the PEHA were also expressed in the form of toxicological benchmark

concentrations for low percentiles (Table 5-5). For example, the data in the table indicate that

5% or less of DO concentrations measured in flow at Main Springs in a representative typical

period would be expected to be at or below a concentration of 4.5 mg/L.

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Table 5-5: Toxicological benchmark concentrations for low percentiles, Main Springs, Eliza Spring,

and Old Mill Spring. Benchmarks based on the DO concentration distributions for the three spring outlets. Likelihood estimates are based

on the 28-day adult mortality and 60-day juvenile growth studies. Source: Woods et al. (2010).

Dissolved Oxygen Concentration

(mg/L)

Percentile

Main

Springs

Eliza

Spring

Old Mill

Spring

1st 4.0 3.9 2.3

5th 4.5 4.4 2.9

The USGS datasets used by Woods et al. reflect an indeterminate and variable mixture of

different regulatory conservation measures over a time period. Moreover, a more representative

dataset that contains additional data, including low-flow data, has been collected by the COA,

and both the COA dataset and the USGS dataset are now accessible and further analyzed

(Turner, 2007; Turner, 2009). Accordingly, a different paired DO concentration-springflow

dataset, in conjunction with the lethal concentration (LCx) statistics of Woods et al. (2010), is

used to associate DO concentration and springflow in estimating the frequency and amount of

take for this HCP. However, as would be expected, the datasets are similar and the general

relationships that resulted from the Woods et al. PEHA are considered valid.

5.2.1.3 Implications and Limitations of Stressor-Response Study

The PEHA and other methods applied in this research are helpful in characterizing some of the

parameters of potential take of the Barton Springs salamander, and by extension, the Covered

Species in the field. There are, however, additional areas of uncertainty. As in all laboratory

studies, the response of the test organisms under controlled conditions may not be the same as

their response to DO concentration variations in the field. Response also varies among

individuals, affecting the precision of mortality estimates. This potential variability is accounted

for by showing a 95% confidence interval around the mean17 of each LCx in Table 5-3 and text in

previous Section, 5.2.1.2, Stressor-Response Study Findings and Applications. The surrogate

species San Marcos salamander appeared to react similarly to Barton Springs salamander among

laboratory treatments when metabolism was monitored, but San Marcos salamander mortality

estimates may or may not align as well with those expected in the Covered Species populations

in the field, particularly in any given time period (Woods et al., 2010). Mortality estimates are

only for adult salamanders, so other life stages may have different or more variable sensitivities

to reduced DO concentration (or increased ionic constituent concentrations) in groundwater.

17 A confidence interval about a mean is an estimate of the uncertainty that that mean, which is the mean of a

sample, represents the true mean of the population. In other words, if 100 samples of the same size were collected

and a 95% confidence interval computed about the mean of each sample, we could say that 95 of the 100 computed

intervals would likely contain the true mean of the population.

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Further gaps in knowledge that would have been useful to examine but were beyond the scope of

the project include how DO concentration (and specific conductance) affects reproduction, egg

development, and hatching (Wood et al., 2010). If other stages—eggs or juveniles—are more

sensitive (show higher LC50), higher DO concentration than that determined for the adult

NOAEL may still constitute a considerable threat. For example, no data are available to evaluate

mortality responses of Barton Springs salamander eggs to DO concentration.

Salamanders will occupy habitat characterized by high and low DO concentration (or other

factors, such as water flow velocities that affect DO availability). Although sensing and

responding to such varying DO conditions may be irrelevant at high DO concentrations, it likely

becomes more important at low DO concentrations. In the salamander stressor-response

experimental program, salamanders clearly perceived and responded to low (or decreasing) DO

concentration—the infrared detection system measured the onset of activity during decreasing

DO concentration and cessation of activity during subsequent increasing DO concentration. In

the field, counts of salamanders tend to decline in Barton Springs when DO concentration

decreases below approximately 5 mg/L (Turner, 2004b). Salamanders in local pockets of low-

DO water may migrate and find higher-DO water, either in the submerged surface environment

outside the outlets (Turner, 2007) or inside the subterranean karst system (Service, 2013b; Hillis

et al., 2001). Water flow velocities in the salamander experiments were, for technical reasons,

fairly low (1 cm/sec), likely resulting in substantial boundary layers (water nearest the bottom of

the flow) with still lower flow velocity and DO concentration. Consequently, another possible

response mechanism to low DO concentration would be for salamanders to increase oxygen

exchange across the gills by disrupting those boundary layers—for example, by bobbing, flicking

their heads, or swimming. The novel stressor-response thresholds observed by Woods et al.

(2010) appear to be satisfactory. But they may be effective only for shorter periods of time than

a typical groundwater drought, during which the metabolic energy required eventually exceeds

the energy gained by incremental benefits to respiration.

Inherent variability in DO concentration and specific conductance exists in the Aquifer and

springs inhabited by the Covered Species, possibly due to poor mixing of waters from different

flow routes discharging along the faults as well as differences in re-aeration potential between

confined and unconfined parts of the Aquifer adjacent to the spring orifices. Microhabitats may

be higher or lower in DO concentration than data measured by the COA. In addition, test

organisms during the laboratory study were not able to move to higher-quality habitat conditions

(that is, areas with higher flow velocities to increase oxygen exchange across the gills), as they

can in the field. On the other hand, sub-lethal effects observed in the laboratory (such as reduced

activity) may not have contributed directly to mortality estimates in the tests, but in the field such

behavioral changes may increase predation risk, reduce foraging, or have other effects that

increase take and even the chances of mortality. Finally, reduced DO concentration may

significantly contribute to cumulative adverse effects with other changes in other springflow-

related and non-springflow-related water chemistry parameters during low flow, which could not

be accounted for in these tests.

Despite the uncertainties that affect the use of laboratory-derived mortality estimates to describe

the mortality risk to the population in the field, the data collected and analyzed by Woods et al.

(2010) provide the best basis to describe the anticipated impact of the Covered Activities on the

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Covered Species and low-flow conditions within the Aquifer and at the Barton Springs complex.

These study results can be used in conjunction with continuous water quantity and corresponding

water chemistry data and salamander survey data collected by the COA, USGS, and the District

to describe parameters of incidental take of the Covered Species under the District HCP. With

estimated responses to changes in DO concentration (Woods et al., 2010) and known

relationships between DO and springflow (Porras, 2014; Turner, 2007) and salamander survey

data during a range of aquifer conditions, it is possible to estimate the response of the Covered

Species to reduced DO concentrations associated with low flows. The estimated responses form

a rational and the best-available basis for determining adverse effects at the organismal level, and

ultimately take, at the population level.

5.2.2 Spatial and Temporal Extent of Take

Take, as defined at 50 CFR 17.3, includes both harm and harassment of the Covered Species.

Harm is defined as “significant habitat modification or degradation where it actually kills or

injures wildlife by significantly impairing essential behavioral patterns, including breeding,

feeding, or sheltering.” Harassment is defined as “annoying wildlife so as to significantly impair

[those] behavioral patterns.”

Estimates of take of the Covered Species within the Aquifer and at the perennial spring outlets

are based primarily on two measurable life requirements of the species: (1) rate of groundwater

flow through the Aquifer as expressed by springflow, and (2) its associated changes in DO

concentrations.18 Both the Covered Activities and natural variability can cause similar

reductions in springflow and DO concentration. However, the Covered Activities can hasten and

reduce springflow and DO concentration beyond the natural variability. The Covered Activities'

influence on springflow and DO concentration that causes harm and harassment to the Covered

Species is the basis for the District’s Incidental Take Permit (ITP).

Using the studies of Woods et al. (2010) described in Section 5.2.1, Experimental Assessment of

Salamander Responses to Changes in Water Chemistry Related to Springflow, the District has

identified two general responses from the species that may constitute incidents of take from the

Covered Activities under certain circumstances. The first is an initial behavioral response when

combined springflows at the perennial outlets are equal to or less than 30 cfs (0.85 m3/s) and the

corresponding DO concentration is equal to or less than 5.0 mg/L, which is the recommended

criterion for karst water quality applicable to the Covered Species (White et al., 2006). The

second is a physiological response when combined springflows are equal to or less than 20 cfs

(0.57 m3/s) and the corresponding DO concentration is equal to or less than 4.5 mg/L (the

NOAEL).

18 Water temperature also may be important in defining the short-term temporal DO conditions, owing to the

reduction in DO solubility with higher temperatures. But temperature effects are reflected primarily in the

variability of DO concentrations observed for a particular springflow. Under base-flow conditions, temperature of

water discharging at the outlets tends to be cooler and more uniform and less likely to control DO concentrations

than the proportion of saline and other older, less meteoric groundwater in springflow (Mahler and Bourgeais,

2013).

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However, while the Covered Activities will be continuously occurring, they do not result in take

during non-drought conditions. When combined springflows are at or above 40 cfs, the

incrementally smaller springflows at the perennial outlets that are partly a result of the Covered

Activities are not accompanied by changes in water chemistry or other habitat characteristics that

have behavioral or physiological relevance to the Covered Species. So the Covered Activities do

not produce take under such circumstances. As noted above, the combined springflow threshold

where take begins at perennial outlets is 30 cfs.

For purposes of this HCP, the District is making an assumption related to adverse effects of

decreases in DO concentration on the Covered Species other than those experimentally

evaluated. In the absence of quantitative flow-specific data, any other potential adverse sub-

lethal effects are assumed to also begin at the same time as the take indicated by the laboratory-

determined physiological responses. Such other sub-lethal effects may be expressed at either the

individual organism level or at the population level. At the organism level, potential effects

include other physiological responses such as impaired egg production and development,

reduction in reproductive success, reduction in recruitment, and/or detrimental behavior. At the

population level, they include reduction and cessation of reproduction, reduction and cessation of

growth, reduction in prey abundance, and increased intra-and inter-specific competition.

The Covered Activities take place over the entire ITP Area and in this well integrated hydrologic

system affect the amount of groundwater flowing through the Aquifer and issuing from the

spring outlets. The resultant take of Covered Species will occur throughout the Aquifer as well

as at or near the spring outlets. Take affects the populations at each outlet to somewhat different

degrees and at slightly different times, depending on the total spring discharge and resultant

water levels and chemistry. Table 5-6 shows the baseline flows and recurrence (nonexceedance)

frequencies (percentage of time flow is at or below a designated rate) for each outlet that

correspond to take resulting from habitat, behavioral, and physiological responses. Combined

flows greater than 30 cfs (DO concentration > 5.0 mg/L) are not considered to annoy, harass, or

harm the Covered Species within the Aquifer or at any perennial outlet as a result of the Covered

Activities; therefore no take occurs. Combined flows greater-than-20 through 30 cfs (4.5 mg/L <

DO concentration ≤ 5.0 mg/L) cause mostly sub-lethal behavioral effects and therefore, annoy or

harass (take) the Covered Species as a result of the Covered Activities. Combined flows equal to

or less than 20 cfs (DO concentration ≤ 4.5 mg/L) cause physiological sub-lethal to lethal effects

and therefore, annoy, harass, or harm (take) a variable portion of the Covered Species as a result

of the Covered Activities.

As drought becomes prolonged and deepens, the effects on individual organisms are likely to

proceed from an initial sub-lethal, annoyance/harassment form of take for a few individuals to a

progressively more harmful form of take that affects increasingly larger numbers of individuals

and that ultimately includes mortality. The rationale and methodology used to develop

thresholds for these effects are discussed in Section 5.2.1.1, Laboratory Study Design. They are

summarized in this section to provide support for this discussion of the spatial and temporal

context for take.

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Table 5-6: Onset of take by spring outlet. Flows and frequencies in the table pertain to the HCP pumping scenario, with 2014 levels of authorized groundwater

withdrawals and after implementation of the set of HCP conservation measures (described in Section 6.2,

Minimization and Mitigation Measures) but without the benefits of the mitigation measures (DO augmentation) or

the COA’s planned HCP activities (re-aeration). Additional explanation is in Appendix J.

Outlet Habitat

Loss (cfs) Recurrence

Frequency

Behavioral

Change (cfs)

when DO

≤5.0 mg/L

Recurrence

Frequency

Physiological

Change (cfs)

when DO ≤4.5

mg/L

Recurrence

Frequency

Main n/a n/a 27 32% 19 19%

Eliza n/a n/a 29 35% 20 20%

Old Mill n/a n/a 29 35% 18 16%

Upper BS* 40 48% n/a n/a n/a n/a

* Upper Barton Springs ceases to flow below 40 cfs, and the corresponding DO concentrations are above the behavioral and

physiological thresholds. Take at Upper BS is associated solely with habitat loss. Conversely, the effects of habitat loss or physical

modification at the perennial outlets at lower flows are negligibly small compared to water-chemistry effects.

Adverse effects also occur due to the incremental physical habitat loss caused by reduced

springflow during recurring drought cycles. This is most noticeable in the temporary reductions

and losses of spring habitat at Upper Barton Spring, a non-perennial overflow spring with a small

population of Barton Springs salamanders. As noted earlier, Upper Barton Spring stops flowing

when combined flow in the Barton Springs complex is less than 40 cfs (1.1 m3/s). This is a

recurring condition related to the elevation of the Upper Barton Spring outlet relative to water

levels in the Aquifer. That is, flow ceases when the water level at the outlet falls below the

elevation of the outlet. This condition would occur about 38% of the time without the Covered

Activities, and it will occur about 48% of the time with the Covered Activities and the HCP

conservation measures in place.

At Upper Barton Spring there is likely no adverse physiological response associated with the

water chemistry at springflows around 40 cfs. This lack of response is supported by the re-

appearance of relatively robust individual Barton Springs salamanders at this outlet when the

Aquifer water level at the outlet rises above the outlet and Upper Barton Spring begins flowing

again (City of Austin, 2013). But it is reasonable to assume that the physical loss of most of the

surface habitat at Upper Barton Spring affects the entire salamander population at this outlet by

causing a retreat of salamanders into the subterranean habitat, and perhaps including migration of

some fraction of the resident population to other outlets. Although no life functions are known

to be permanently impaired for these species by this inherent and frequently recurring loss of

physical habitat, the population is reasonably inferred to be annoyed, and some adverse effects

on feeding and sheltering behavior are likely. Because withdrawals contribute to the decline of

water levels in the Aquifer (even though only a very small fraction at springflows around 40 cfs

when physical habitat loss starts to occur), some portion of the adverse effects on the Upper

Barton Spring population, primarily a sub-lethal form from annoyance and harassment, is

attributable to the Covered Activities and is therefore take.

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5.2.3 Consideration of Take and Jeopardy

The populations at or near each outlet at a given time are potentially adversely affected by

changes in flow and water chemistry at the respective outlet, as well as within the Aquifer. As

described in Section 5.2.2, Spatial and Temporal Extent of Take, at least a fraction of that

adverse effect is created by decreased springflow derived from withdrawals by nonexempt

permitted wells, the Covered Activity. Therefore take occurs, and the amount of take depends on

the size of the population that exists at a given time and the proportion of adverse effects that are

associated with natural variations in springflow that would occur regardless of the Covered

Activities. When non-drought conditions are re-established, the adversely changed

characteristics of groundwater flow may no longer exist, but the take incident associated with the

just-ended drought has already occurred and does not decrease. So incidents of take are

estimated on the basis of a correlation between springflow and DO concentration and are

cumulative over multiple District-declared droughts that will occur during the ITP term.

5.2.3.1 Characteristics of Populations Adversely Affected by Take

The approaches that the District uses to estimate the sizes of the populations and

superpopulations that are affected by take of the two Covered Species are described in detail in

Section 3.2.2.2.1, Habitat Characteristics and Supported Populations. The relationships between

the populations and the causes and types of their take that occur as a result of the Covered

Activities are addressed in this subsection.

Barton Springs Salamander

Two cohorts of the Barton Springs salamander occur, and both the near-field and far-field

cohorts are subject to take. Much more information is available for the near-field cohort to

characterize both its population and take. The COA has regularly conducted surveys of the

Barton Springs salamander at the Barton Springs outlets since 2003 (City of Austin, 2013).

Since 2014, the COA has been using a more sophisticated robust capture-mark/release-recapture

(CMR) survey program on an approximately quarterly basis, supplemented with enhanced

analysis for estimating the abundance of the superpopulation of this near-field cohort (City of

Austin, 2017a). The statistics and analyses on abundance, density, and their variation from these

two investigative approaches (City of Austin, 2017a; 2013) provide internally consistent,

extensive datasets from which to gauge the size of the surface population of the near-field cohort

of this species. These datasets are believed to provide a sound basis for the District’s estimate of

take of the near-field cohort of the Barton Springs salamander.

The COA noted in its Barton Springs Pool HCP that salamander abundance based on survey

counts at the spring outlets varies with environmental conditions (City of Austin, 2013).

Accordingly, the District considers the actual salamander population present in a perennial outlet

during periods when its DO concentration is below the salamander take threshold to be the

adversely affected near-field population. To reduce this adversely affected population to a single

numerical estimate as required for the ITP, the District has designated the number of individuals

experiencing incidents of adverse effects arising from DO-related behavioral or physiological

effects at the spring outlets to be equivalent to the entire CMR-based abundance data from the

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COA’s at each outlet. This metric represents the near-field population that experiences adverse

behavioral or physiological effects from low DO concentrations related to changes in the

springflow regime. The metric incorporates and reflects a measure of variability from

environmental and other factors that affect counts as well as a central tendency. In contrast to

this approach, the COA used a “mean-plus-one SD” approach, indexed to salamander densities

observed in specific subareas, to account for those variable effects in estimating take in the

COA’s subarea-specific covered activities (City of Austin, 2013). The more rigorous CMR-

based abundances were not available at the time of the COA’s ITP and HCP development.

Abundance data for the far-field cohort of the Barton Springs salamander is extremely sparse,

and only rudimentary statistical analyses are available for making an estimate of the population

of this cohort. As described more fully in Section 3.2.2.2.1, Overview of Habitat Characteristics

and Supported Populations, the District has made what it considers a rational set of assumptions

to develop a first-order informed estimate of this cohort’s abundance. But it is based only on the

single location in the far-field (Blowing Sink Cave) where count data and preliminary density

analysis exist. It assumes that the spatial distribution of this far-field subsurface cohort is

concentrated along the primary and secondary groundwater flow routes, rather than being more

or less uniformly dispersed throughout the Aquifer.

Table 5-7 provides a summary of the total populations and locations of the Barton Springs

salamander that encounter adverse effects from the Covered Activities. The actual populations at

any specific time and at or near any specific outlet will vary, ranging on either side of these

average superpopulation estimates. All of these outlets in the Barton Springs complex are

hydrologically interconnected, so migration of individual organisms among certain outlets is

possible.

Table 5-7: Total stipulated population of the Barton Springs salamander by location.

Location Stipulated Population

Main Springs (Near-field) 181

Eliza Spring (Near-field) 855

Old Mill Spring (Near-field) 37

Upper Barton Spring (Near-field) 15

Remote Population (Far-field) 3900

Total Stipulated Population 4988

Unlike the perennial outlets, the entire surface habitat of non-perennial Upper Barton Spring is

lost when the combined Barton Springs flow decreases below 40 cfs, even though the DO

concentrations at the outlet remain high. So its entire stipulated population is considered to be

adversely affected immediately upon entry into drought, even though the effects are not

physiological and may be mostly non-lethal.

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Austin Blind Salamander

Two cohorts of the subterranean Austin blind salamander are inferred to exist, the near-field and

far-field cohorts, but there is little reliable data known about the populations of either. Surface-

habitat surveys of the Austin blind salamander conducted by the COA (and that are useful for its

covered activities) are not considered to accurately reflect the population of even the near-field

cohort of that subterranean species, at any one or all outlets. As explained in Section 3.2.2.2.1,

Overview of Habitat Characteristics and Supported Populations, the District has estimated the

size of this cryptic population by using a set of inferences and assumptions that yields an

approximation of the population size of the near-field cohort, for purposes of the District’s HCP.

It essentially defines the near-field as the Service-designated Critical Habitat Area for the Austin

blind salamander. The spatial distribution of the near-field cohort population at the various

outlets is indexed to the proportionate estimated amount of springflow at the individual outlets

during Stage III Critical- or more severe drought, viz., when the combined flows of Barton

Springs are at or less than 20 cfs, under a reasonable presumption that higher groundwater flows

and velocities will be physiologically preferred as sub-habitat for this Covered Species.

To date, there have been no reported occurrences of Austin blind salamander in the far field. The

far-field cohort of this Covered Species may or may not exist. But as previously noted, it seems

likely that some individuals are present from time to time outside the near-field habitat, even if

they do not represent a separate population but simply a local, transient migration of some

individuals beyond the Critical Habitat Area boundary. In absence of any data or other

information, the District has simply stipulated a far-field cohort size that is nominally 5% of the

near-field cohort. Should additional significant information be developed during the ITP term

concerning the distribution of ABS, either among the outlets or between the near-field and far-

field, the District will consider those impacts on population size and/or take as a Changed

Circumstance (see Section 7.2.2.1).

Table 5-8 provides a summary of the total populations and locations of the Austin blind

salamander that may encounter adverse effects from the Covered Activities.

Table 5-8: Total stipulated population of Austin blind salamander by location.

Location Stipulated Population

Main Springs (Near-field) 877

Eliza Spring (Near-field) 111

Old Mill Spring (Near-field) 12

Upper Barton Spring (Near-field) 0

Remote Population (Far-field) 50

Total Stipulated Population 1,050

Both Covered Species

For purposes of this HCP, the District is considering that the same water chemistry, in particular

dissolved oxygen concentration and salinity, as measured at the Aquifer outlets at any particular

time also apply to all groundwater then flowing through the Aquifer, at least during low-flow

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(non-stormflow) drought conditions that are of most import to evaluating the Covered Activities.

In turn, the same adverse effects and consequent impacts from the Covered Activities occur to

both near-field and far-field populations of the Covered Species at the same time and may be

assessed in an aggregated fashion by the same method. This probably is a rather conservative

assumption, in that, on average, the subterranean waters in the unconfined, transitional, and

upper parts of the confined geohydrologic zones of this Aquifer probably are not as affected by

DO-depleted waters deeper in the confined zone (e.g., Lazo-Herencia et al., 2011), which issue at

the perennial Barton Springs outlets during drought.

This HCP does not quantitatively differentiate sub-lethal effects from changes in DO

concentration on reproduction, natality (birth rate), recruitment (rate at which juveniles mature to

reproduction age), reducing other growth, reducing prey/food abundance, and increasing intra-

and inter-specific competition (Gillispie, 2011). Similarly, it does not quantitatively differentiate

potential adverse effects arising from these other causes from adverse physiological response or

behavioral effects arising from changes in DO concentration. To the District’s knowledge,

quantitative relationships between and among these factors for either of the Covered Species do

not exist. Individually, they are assumed to be small relative to the behavioral or physiological

effects associated with DO reductions in springflow, but in aggregate and cumulatively, they

may produce appreciable adverse effects. In this HCP, behavioral effects related to DO are

considered mostly non-lethal take, and physiological effects related to DO may start as non-

lethal but progress over time to lethal, along an unquantified and probably temporally variable

trajectory. This HCP has found no basis to parse or differentiate quantitatively the non-lethal and

lethal effects on the Covered Species by the Covered Activities.

5.2.3.2 Apportionment of Springflow-related Take to Adversely Affected

Populations

To quantify incidents of take, the District has developed a monthly “take factor” that accounts

for both lethal and sub-lethal forms of take of each species by the Covered Activities when

springflow is below 30 cfs (0.85 m3/s). To arrive at these factors, the District has integrated

laboratory results (Poteet and Woods, 2007; Woods et al., 2010), long-term field observations,

regulatory program requirements, hydrogeologic modeling (Smith and Hunt, 2004), and

statistical modeling to estimate the adverse effects and percentages of the stipulated populations

that experience incidents of take. The District constructed a step-wise (spreadsheet) model of

springflow, withdrawals, management scenarios, and DO correlations on a monthly basis over

the 97-year period of record (Appendix J). The model provides detailed information on the

hydrologic relationships, statistics, and rationale used to inform the HCP. The following are

definitions of terms used in the modeling scenarios discussed in this section (Section 5) and

Appendix J:

a. Groundwater Management Scenarios

1. Exempt-only Pumping – a baseline scenario that results in springflow without effects of

the Covered Activities (that is, without effects of nonexempt permitted pumping).

2. Pre-HCP Pumping – a scenario that represents conditions that existed in 2004, just before

the HCP program and preemptive conservation measures were initiated.

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3. HCP Pumping – a scenario that represents conditions after implementation of the

proposed conservation program for the Covered Activities, with all proposed HCP

measures to avoid, minimize, and mitigate take of the Covered Species.

b. Reference Droughts

1. Drought of Record (DOR) – the severe drought of the first seven years of the 1950s.

2. Recent Severe Droughts (RSD) – a series of three severe droughts from mid-2005 to mid-

2012, which includes the groundwater drought of 2009 that resulted in the lowest Aquifer

water levels since the District was formed in 1987, and the 2011 drought that produced

the driest, hottest single year in Texas history.

3. Hybrid Drought – a synthetic seven-year drought that was defined for this HCP and that

combines springflows from the DOR and the RSD on a month-by-month basis, with

DOR springflows weighted twice those of the RSD. The District considers this the worst

drought reasonably expected to occur during the 20-year term of the ITP.

Figure 5-5 shows the recurrence (nonexceedance) frequency of springflow over the 97-year

period of record as it would exist under each of the three groundwater management scenarios.

The benefit of the HCP pumping scenario, with measures to avoid, minimize, and mitigate take,

compared to the pre-HCP pumping scenario is particularly noticeable at springflows less than

about 30 cfs, when adverse behavioral effects begin to occur.

Similarly, the District related measured DO concentrations associated with the various combined

springflows using linear regression analysis to develop the nonexceedance frequency of DO

concentration for springflow under each of the three management (pumping) scenarios. Each

outlet has its own DO concentration-springflow relationship, and therefore nonexceedance

frequency is outlet-specific (Figure 5-6 a, -b, and -c). More information on the development of

these graphs for the three perennial spring outlets is in Appendix J.

Figure 5-7 focuses on the springflow variations that would result from the three groundwater

management scenarios during the severe drought conditions of a DOR recurrence and as they

relate to the 30- and 20-cfs (0.85-0.46 m3/s) thresholds for estimating take.

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Figure 5-5: Recurrence (nonexceedance) frequency of Barton Springs flow for the period of record

under three groundwater management scenarios. The effect of the HCP conservation measures becomes increasingly more beneficial compared to the pre-HCP

scenario as flows less than about 30 cfs (dashed line) continue to decrease.

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Figure 5-6a: Nonexceedance frequency for dissolved oxygen concentration for the period of record

at Main Springs under three groundwater management scenarios. The HCP measures reduce the frequency of low DO concentrations and associated degree of harm that result from

nonexempt pumping. These curves do not reflect the benefits of the mitigation measures (DO augmentation).

Figure 5-6b: Nonexceedance frequency for dissolved oxygen concentration for the period of record

at Eliza Spring under three groundwater management scenarios. The HCP measures reduce the frequency of low DO concentrations and associated degree of harm that result from


113

Figure 5-6c: Nonexceedance frequency for dissolved oxygen concentration for the period of record

at Old Mill Spring under three groundwater management scenarios. The HCP measures reduce the frequency of low DO concentrations and associated degree of harm that result from


114

Figure 5-7: Modeled Barton Springs flow during DOR conditions under three groundwater

management scenarios. The relationships between flow under each management scenario and the 30- and 20-cfs thresholds important to take

estimates are indicated. In the deepest parts of very severe drought, springflow resulting from each of the three

scenarios is below the 20-cfs threshold.

The concept and rationale used to estimate take and develop the monthly “take factor” are

illustrated in Figure 5-8 and Table 5-9. The 37 month period at the end of the DOR was selected

as a discrete worst-case drought scenario to estimate the total take and then to derive the monthly

take factor. This roughly 3-year period, deep in the DOR, provides a long-term, consistent basis

for differentiating take from other adverse effects during the key periods of severe droughts,

while incorporating month-to-month temporal variations. No distinction is required or was made

between near-field and far-field population cohorts in the take assessment. Full implementation

of the HCP measures is assumed, but without the benefits of the mitigation measures (DO

augmentation) or the COA’s planned HCP activities (re-aeration). Best professional judgment

was used to define the circumstances that relate to estimated take associated with this drought

scenario, as outlined below:

Circumstance A: As combined springflows decrease to about 40 cfs (1.13 m3/s), Upper

Barton Spring ceases flowing. Withdrawals hasten the cessation of flow and loss of habitat;

therefore 100% of the stipulated population of 15 Barton Springs salamanders is taken owing

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to the Covered Activities. The take could be considered mostly sub-lethal, primarily

annoying and harassing, rather than harming the species. For purposes of take estimates in

this HCP, no Austin blind salamanders are considered to have habitat uniquely associated

with Upper Barton Spring; only one ABS individual has ever been observed at this outlet.

Circumstance B: Springflow equal to or below 30 cfs (DO concentration ≤ 5.0 mg/L) and

above 20 cfs (DO concentration > 4.5 mg/L) may result in a behavioral response from the

Covered Species within the Aquifer and its outlets. Withdrawals hasten springflow decrease;

therefore, 100% of the stipulated population of the Barton Springs salamander (4988) and

Austin blind salamander (1,050) are taken owing to the Covered Activities during the two

months within Circumstance B for the reference drought period. The take could be

considered mostly sub-lethal, primarily harassing, rather than harming the species.

Circumstance C: Springflow decreases to 20 cfs or below (DO concentration ≤ 4.5 mg/L),

which may result in a physiological response from the species within the Aquifer and its

outlets. This part of the drought is where the more adverse effects on the entire stipulated

population are likely to occur due to the duration, low springflow, and DO concentration.

Covered Activities contribute to but are not solely responsible for low springflow and DO

concentration that result in physiological responses that annoy, harass, and ultimately harm

the Covered Species. To apportion the take attributable to the Covered Activities, the ratio of

permitted pumpage under the HCP conservation program to the total discharge for the 35-

month period was used. Permitted HCP pumpage for the 35-month period during

Circumstance C was 4.8 cfs (0.14 m3/s); total discharge for the 35-month period was 16.7 cfs

(0.47 m3/s). Accordingly, about 29% of the stipulated population for each species is taken

owing to the Covered Activities. Average DO concentration for Main Springs during this 35

month period (spreadsheet model which includes HCP measures) is about 3.7 mg/L.

The total take upon aggregating Circumstances A, B, and C for this selected drought period in

Figure 5-8 is estimated to be 6,450 Barton Springs salamanders. That number is then divided by

the period when combined flow was below the take-initiation threshold (30 cfs), 37 months for

the selected drought period (2 months in Circumstance B and 35 months in Circumstance C).

The calculated average take factor for the Barton Springs salamander is 174 incidents for each

month below 30 cfs. Using the same method and logic for the Austin blind salamander results in

a take factor of 36.6 incidents per month below 30 cfs. The difference in take factors between the

Covered Species is due to the difference in the stipulated sizes of the populations, especially in

the estimated abundance of the far-field cohort of Barton Spring salamander.

Table 5-9: Derivation of monthly take factors for Covered Species during droughts.

Species Stipulated

Population

Take Circumstance Total

Take

(A+B+C)

Months

Below 30

cfs

Take Factor

(monthly below

30 cfs)

A B C

Upper BS Behavioral

Effects Physiological

Effects

BSS 4988 15 4988 29% x 4988 =

1447 6450 2+35 = 37 6450/37=174

ABS 1,050 0 1,050 29% x 1050 =

305 1355 2+35 = 37 1355/37=36.6

BSS = Barton Springs salamander; ABS = Austin blind salamander.

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Figure 5-8: Diagram showing reference period and logic used for computing the monthly take

factor.

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The take factor is a conservative approach to estimating the potential incidents of take due to the

Covered Activities for future drought scenarios. In effect, it considers each month of any drought

as if it could be part of the worst period of the DOR. The factor integrates complicated aspects of

take assessment to provide a simple, yet systematic approach to measuring, monitoring, and

reporting incidents of take going forward.

5.2.3.3 Consideration of Take Not Related to Springflow

In addition to the take related to springflow that occurs on a more or less continuous basis during

drought, there are also take instances related to discretionary activities that may occur

occasionally at other times and from time to time. Generally, this occasional take is related to

research projects and conservation measures that are uniquely specified in this HCP, especially

installation and/or implementation of mitigation measures that may be undertaken from time to

time in the vicinity of the spring outlets. The mitigation measures are by definition designed to

avoid or minimize take related to springflows, so there is a net benefit to the Covered Species in

that regard during the implementation of the mitigation. Moreover, the take incidents from the

two causal types at any given time are not likely to be contemporaneous and cumulative with

each other, because the take associated with construction of mitigation and research facilities,

such as installation of DO augmentation wells and habitat assessment wells, would not be

undertaken during drought conditions when the Species are more stressed by low springflows.

Nevertheless, the amount of occasional take also needs to be estimated and included in the

calculation of total take associated with the (mitigated) Covered Activities.

Only a coarse estimate of occasional take is possible with data currently available. The District

has used (i) the subsurface footprint made by installing, casing, and developing an oxygen-

augmentation well in the subterranean habitat, and (ii) the presumptive subterranean density of

the Austin blind salamander, to estimate that each such well could harass or harm no more than 2

individuals. While the number of these wells, if any, has not been determined, the aggregate take

from this activity is likely no more than 10 Austin blind salamander individuals, and the take is

likely to be dominantly of non-lethal form. It is less likely that the Barton Springs salamander

would be harassed or harmed by this type of activity, because its habitat is in the immediate

vicinity of the outlets and the wells are likely to be some distance up-gradient from the outlets to

avoid flow disruption, but a nominal occasional take of 5 Barton Springs salamander individuals

has been included. This take, if it occurs at all, will only take place once during the entire ITP

term, during the period of time when the augmentation wells are installed.

In addition, certain scientific investigations that are part of the proposed HCP research program

may be conducted at or near the spring outlets. These include surface surveying, surface-water

monitoring, near-field dye tracing, and surface geophysical surveys. It is possible that a very

small amount of take could be associated with these activities, but there is no sound basis for

making a quantitative estimate of them. The District simply stipulates for the purposes of the

HCP/ITP that no more than 10 Barton Springs salamanders and 5 Austin blind salamanders will

be taken by such activities over the course of the ITP term.

These sources of occasional take of the Covered Species have not been included in the City of

Austin Barton Springs Pool HCP and ITP, so they are additive. The District and the City will

coordinate their activities to minimize the amount and frequency of take from such activities, to

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be specified by the negotiated Memorandum of Understanding/Inter-local Agreement between

the entities.

5.2.3.4 Cumulative Take Estimates

Incidents of take over the entire term of the ITP will depend on the drought conditions that

actually occur over that particular 20-year period. Take related to springflows from the Covered

Activities only takes place during drought periods, which over the long term occurs roughly one-

half the time. The amount of take varies with the severity and the length of the drought period.

Droughts are not uniformly distributed in either severity or time over any 20-year period of time,

and within any shorter multi-year drought period there will be some months or even years of no

drought. The following cumulative scenario is proposed as a basis for assessing and estimating

cumulative take during the ITP term, using the drought stage terminology that triggers various

District Rules-based drought management strategies:

1. One seven-year period of Extreme Drought, equivalent to the DOR;

2. One seven-year period of Stage IV Exceptional Drought, equivalent to the Hybrid Drought;

3. Six years of no drought, during which no take of any kind occurs and the Covered Species

populations recover to their stipulated populations as modeled initial conditions (Table 5-9).

This cumulative take scenario is just one possible scenario for a 20-year period, but it is, in the

judgment of District hydrogeologists, a very conservative, even worst-case scenario from a

hydrologic standpoint. This scenario should not be considered a prediction of what will happen

annually during the ITP term, rather it is simply the basis for calculating cumulative take to be

specified in the ITP. That said, the six-year period of no drought, in which no behavioral or

physiological take would occur, accommodates the need for the Covered Species to rebound to a

level approximating the initial condition at the beginning of a severe drought, as used in the

model. The COA’s continuing low survey counts after the recent severe drought period that

ended in 2011 suggest that at least some if not all outlets may need this much or more time for

the populations to fully recover. The slow recovery and continued low abundance numbers may

also be exacerbated by other factors not related to springflow and/or not caused by the District

HCP’s Covered Activities, and therefore may not be considered take.

As noted in the previous subsection, occasional take associated with prospective research and

mitigation activities must be added to the take associated with springflows.

This scenario yields cumulative take estimates for the Barton Springs salamander and the Austin

blind salamander shown in Tables 5-10 and 5-11, respectively. The tables show the number of

individual incidents of take for each by the Covered Species over the 20-year ITP term with the

HCP conservation measures in place.

The actual amount of take incurred in any multi-year drought scenario will depend, other factors

equal, on the actual initial size of the populations when the drought period begins. Because the

species populations are typically variable, the take could be less than the amount shown, as the

initial conditions used in this analysis are a best estimate corresponding to stipulated population

sizes at or near the top of a cycle. The distribution of take with time during the seven years of

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the severe droughts will depend on the variability of annual meteorological and hydrological

conditions. It is no more likely that the take will be spread evenly across the seven-year time

span than it will occur over one or two years in that span.

Table 5-10: Summary of cumulative take of Barton Springs salamander for 20-year ITP term.

Drought/Springflow Scenarios

(As Defined by Modeled Hydrographs in

Appendix J)

No. Months

below 30 cfs

(Per Modeled

Hydrographs)

Take/Month

(Table 5-9) Total Take

7-Year DOR 72 174 12,528

7-Year Hybrid Drought 44 174 7656

6 Years No Drought 0 174 0

Occasional Activities (in aggregate) 15

Cumulative Total for ITP 116* 20,199 ~ 20,200

* This is a conservative estimate for a 20-year period. Over a period from January 1993 through October 2013 (~21 years) Barton Springs

monthly flow was below 30 cfs about 55 months out of 250 months—or about 22% of the time. During that same period Barton Springs had

about 5 years of consecutive non-drought conditions (November 2000 through December 2005).

Table 5-11: Summary of cumulative take of Austin blind salamander for 20-year ITP term.

Drought/Springflow Scenarios

(As Defined by Modeled Hydrographs

in Appendix J)

No. Months

below 30 cfs

(Per Modeled

Hydrographs)

Take/Month

(Table 5-9) Total Take

7-Year DOR 72 36.6 2,635.2

7-Year Hybrid Drought 44 36.6 1,610.4

6 Years No Drought 0 36.6 0

Occasional Activities (in aggregate) 15

Cumulative Total for ITP 128* 4,261 ~ 4,260

* This is a conservative estimate for a 20-year period. Over a period from January 1993 through October 2013 (~21 years) Barton Springs

monthly flow was below 30 cfs about 55 months out of 250 months—or about 22% of the time. During that same period Barton Springs had about 5 years of consecutive non-drought conditions (November 2000 through December 2005).

The effect of the activities covered by the COA’s ITP, including specifically its Barton Springs

Pool HCP conservation measures, must also be considered in the District’s cumulative take

estimate and impact assessment, and in the Biological Opinion by the Service. The COA’s

covered activities are mostly scheduled recurring activities subject to postponement or

cancellation during periods when the Covered Species are under duress from natural or

anthropogenic causes. While also subject to annual limits, the total cumulative take during the

COA’s 15-year ITP is 38,365 Barton Springs salamanders and 1,025 Austin blind salamanders,

reflecting the recurring, frequent, episodic, and to some extent discretionary covered activities

associated with the Barton Springs Pool HCP. The District’s cumulative take estimates for its

Covered Activities, which are continuous and largely non-discretionary, are 20,200, or 53%, and

4,260, or 416%, of the COA’s cumulative take of Barton Springs and Austin blind salamanders,

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respectively. (The disparity in the take comparison percentages between the species is because

the COA’s activities cause take of only incidental numbers of Austin blind salamanders in the

surface environments of the outlets, rather than in both the surface and subterranean

environments as the District’s Covered Activities potentially do.)

The COA’s and the District’s take estimates are not likely to be completely contemporaneous

and cumulative. At times when the District’s take and its impact are maximum, the COA is

likely to have suspended, postponed, or canceled its pool maintenance operations under the terms

of its HCP/ITP (although recreational activities may continue), and the COA’s take at those

times will be near a minimum. Further, the mitigation measures the COA has committed to will

benefit the Covered Species even though not all of its covered activities are underway. The

District and the COA will strive to minimize cumulative impacts in this regard by formalizing

respective commitments and needed actions in the prospective Memorandum of

Understanding/Interlocal Agreement (MOU/ILA) between the two agencies, which is a

commitment in the HCPs of both entities. This MOU/ILA will be negotiated within the first year

after the District’s HCP and permit are approved.

5.2.3.5 Considerations for “No Appreciable Reduction” Analysis

The effects of incidental take associated with the Covered Activities must not appreciably reduce

the likelihood of the survival and recovery of the Covered Species in the wild—that is, cause

jeopardy, per the Service’s ITP issuance criteria (Section 2.3.2, Findings for the Service to Issue

an ITP). Jeopardy occurs when an action is reasonably expected, directly or indirectly, to

diminish a species’ numbers, reproduction, or distribution so that the likelihood of survival and

recovery in the field is appreciably reduced. The analysis of jeopardy is referenced to baseline

conditions that include incidental take of the same species from other activities under any other

HCP as well as the avoidance, minimization, and mitigation measures associated with it.

As severe droughts deepen, the form of take changes from principally sub-lethal to lethal as DO

concentration decreases. The phenomenon of decreasing DO concentration is characterized in

detail in Appendix J and only highlighted in this section. Estimates of low DO concentration

associated with the Covered Activities and drought are shown in Figures 5-9a-c, and 5-10a-c,

with different graphs for each of the three perennial outlets and two different figures for the

Hybrid Drought and DOR modeled scenarios, respectively. For example, in the Hybrid Drought

in Figure 5-9a, with the conservation measures in place, the springflows at Main Springs will be

below 30 cfs (below about 5.0 mg/L DO) for about 38 months during its seven-year drought

period, and the DO concentration reaches 4.0 mg/L at Main Springs for three months during that

seven-year drought.

Impacts associated solely with natural flows and exempt-only pumping increase substantially as

the droughts deepen and become more extreme. Figure 5-10, depicting a recurrence of the DOR,

shows that DO concentration with the HCP measures, including DO re-aeration from spring-run

improvements (a measure of the Barton Springs Pool HCP) and DO augmentation (a mitigation

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of this HCP)19, is not much different than DO concentration without the Covered Activities

(exempt-only pumping). Figure 5-10 shows that DO concentration with the HCP measures

including DO re-aeration from spring-run improvements and DO augmentation (dashed line in

Figure 5-10) matches or exceeds the DO concentration of the exempt-only pumping scenario—

indeed, the average DO concentration for both pumping scenarios during the DOR is 4.8 mg/L.

However, during the months of lowest springflow (July and August 1956), the scenario of HCP

pumping including DO re-aeration from spring-run improvements and DO augmentation results

in DO concentration about 1 mg/L below that of the exempt-only pumping scenario. However,

the model conservatively correlates flow and DO concentration (Porras, 2014) and assumes only

modest gains from DO augmentation of about 0.5 mg/L. The conservatively low DO

concentrations and assumed modest gains from DO augmentation reinforce the importance of the

conservation measures in avoiding, minimizing, and mitigating decreases in DO and

accompanying take.

As suggested in Figure 5-10, the Covered Activities under the pre-HCP management scenario

represent a dire adverse situation for the Covered Species, possibly including extirpation. Any

groundwater management measures that minimize and mitigate take, like this HCP’s

conservation measures, such that the situation is less adverse than it otherwise would be,

generally should be considered as appreciably increasing the likelihood of survival and recovery

of the species, rather than decreasing such likelihood. The HCP for the Edwards Aquifer

Recovery Implementation Plan (EARIP) in the San Antonio segment of the Edwards Aquifer

reached a similar conclusion.

This HCP has noted elsewhere the many uncertainties, assumptions, and stipulations required in

making a quantitative take estimate for the Covered Species by the Covered Activities. Several

of these in particular bear on assessing the likely risk of an appreciable reduction in survival and

recovery:

Probabilities of recurrence of the modeled droughts – The take estimate includes modeling of

both a reasonable worst-case drought scenario for the 20-year ITP term (the Hybrid Drought) and

an unreasonable worst-case drought scenario for the ITP term (the DOR). It is considered very

unlikely that the adverse effects in the modeled cumulative scenario would occur during the ITP.

However, a severe drought such as the DOR, while not considered per se a reasonable basis for

take estimates, could be considered part of an assessment of jeopardy. But the DOR has an

estimated recurrence frequency of 100 years. The seven-year reference droughts (Section

5.2.3.2, Apportionment of Take to Adversely Affected Populations) used in this HCP have the

19 The Eliza Spring Daylighting Project, which is now essentially completed, will provide, among other benefits to

the Covered Species, a continuous mechanism to increase the DO in the water issuing from Eliza and supporting its

salamander population. The District conservatively estimated that the DO would increase in the spring run only by

0.3 mg/L DO, which is more than an order of magnitude less than typical reaeration amounts associated with

analogous cascade reaeration runs at the outfalls of treated wastewater. The DO Augmentation Project is a

prospective mitigation measure described in Sections 6.2.2.2 and subject to the provisions of Section 7.2.2.of this

HCP, and would be operated, if demonstrated as feasible, in cooperation with the City of Austin under an

ILA/MOU. It is designed to increase the DO concentration at the outlets, as needed, to at least 4.5 mg/L during the

time it is operated. For purposes of take and jeopardy assessment, the DO benefit from DO Augmentation is

conservatively modeled as achieving only a 0.5 mg/L increase in DO.

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Figure 5-9a: Dissolved oxygen concentrations at Main Springs during prolonged, severe (Hybrid)

drought under three groundwater management scenarios. These concentrations do not reflect the benefits

of the mitigation measures (DO augmentation) at this outlet.

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Figure 5-9b: Dissolved oxygen concentrations at Eliza Spring during prolonged, severe (Hybrid)

drought under three groundwater management scenarios. These concentrations do not reflect the benefits

of the mitigation measures (DO augmentation), but do contain the benefits of ongoing spring-run improvements

(daylighting).

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Figure 5-9c: Dissolved oxygen concentrations at Old Mill Spring during prolonged, severe

(Hybrid) drought under three groundwater management scenarios. These concentrations do not reflect

the benefits of the mitigation measures (DO augmentation, but do contain the benefits of planned spring-run

improvements .

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Figure 5-10a: Dissolved oxygen concentrations at Main Springs during DOR conditions under

three groundwater management scenarios and proposed mitigation measures. The light-green HCP line does not include any mitigation benefits, and the dark-green HCP line illustrates the effect

of a modest amount of DO augmentation (+0.5 mg/L) as proposed mitigation, improving estimated DO

concentration all or most of the time relative to all pumping scenarios, including exempt-only pumping.

.

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Figure 5-10b: Dissolved oxygen concentrations at Eliza Spring during DOR conditions under three

groundwater management scenarios and proposed mitigation measures. The light-green HCP line takes into account planned DO re-aeration (daylighting) from spring-run improvements

(+0.3 mg/L), and the dark-green HCP line illustrates the effect of a modest amount of DO augmentation (+0.5 mg/L)

as proposed mitigation, improving estimated DO concentration all or most of the time relative to all pumping

scenarios, including exempt-only pumping.

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Figure 5-10c: Dissolved oxygen concentrations at Old Mill Spring during DOR conditions under

three groundwater management scenarios and proposed mitigation measures. The light-green HCP line takes into account DO re-aeration from planned spring-run improvements (+0.3 mg/L),

and the dark-green HCP line illustrates the effect of a modest amount of DO augmentation (+0.5 mg/L) as proposed

mitigation, improving estimated DO concentration all or most of the time relative to all pumping scenarios,

including exempt-only pumping.

.

following probabilities of occurrence, as calculated by the District for this HCP over the 97-year

period of record used by the District (see Section 3.2.2.1.2, Sources and Implications of

Variation in Springflow at Barton Springs):

Recent Severe Drought (2005–12) 57%

Hybrid Drought 11%

Drought of Record (1950–57) 1%

The likelihood that both the Hybrid and DOR droughts would occur in any single 20-year period

within the 97-year period of record is much smaller even than those shown, which tends to offset

concerns about indeterminate future climate change effects during the relatively short ITP term.

Further, it is so unlikely that there will be a DOR recurrence in any given 20-year period that its

improbability must be taken into account when judging the likelihood of the risk of an

appreciable reduction in survival and recovery.

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Migration of animals to less-stressful parts of the habitat – The modeling used for estimating

take purposefully included only minimally the reasonable likelihood that, but unquantifiable

extent to which, both species would migrate to areas adjacent to the outlets where DO

concentration was higher and thus DO-related stress lower. It seems reasonable that some

portion of the Austin blind salamander population will move from the immediate vicinity of the

outlets where DO concentration is depressed to adjacent connected areas within the Aquifer,

especially to subterranean areas at or near the water table, where the atmospheric interface

results in generally higher DO concentration (Lazo-Herencia et al., 2011). In addition, the

proposed DO augmentation project that is a conditional mitigation measure may provide

supplemental benefits in the vicinity of the outlets. For the Barton Springs salamander, the

benefit from re-aeration created by the planned but not yet available spring runs and by the

conditional DO augmentation that is a potential mitigation measure has also been conservatively

estimated in the cumulative loss evaluations. Sensitivity analyses done for this HCP, indicated in

the results shown in Figure 5-10 and in Appendix J, suggest that the benefits to the salamander

population of relatively small amounts of DO stress relief are disproportionately large, especially

the mitigation provided by DO augmentation.

Benefit of evolutionary life-history strategies – The Covered Species have population

characteristics and individual organism traits that appear to represent more an “opportunistic”

life-history strategy than an “equilibrium” life-history strategy20. Some opportunistic population

characteristics include relatively large swings in population sizes over multiple-generation time

periods, rather than smaller fluctuations around a mean that is a defined “carrying capacity,”

rapid growth and development of individual organisms, numerous offspring at a time,

reproduction that is more or less continuous if environmental conditions are not limiting, and

lack of post-natal and parental care (which otherwise would emphasize and promote better

competition by a few individual offspring rather than depending on a “numbers game”). Such

characteristics connote evolutionary development of the Covered Species in response to frequent

occurrences of disturbances like droughts and floods in their springflow-dominated environment.

Floods and droughts cause indiscriminate, density-independent mortality and then recovery of

the residual population based on the availability over time of resources in their habitats (Pianka,

2000). Opportunistic species generally may accommodate larger adverse effects related to

constrained resources (such as low DO concentration, within limits) that governed their

evolution without jeopardizing the species more than could equilibrium species. In a related vein,

Issartel et al. (2009) notes that the evolutionary ability for subterranean salamanders to tolerate

hypoxic to highly anoxic conditions, while well established, evidently differs among such

species, owing to differences in metabolic controls that are poorly understood; that study did not

specifically address the Covered Species.

This aspect of the populations of the Covered Species may have been a key to the survival of the

species during multiple prolonged and severe droughts through the millennia, and therefore to

20 The terms “opportunistic” and “equilibrium” have been used as short-hand descriptors for a complex set of

evolutionary life-history causative factors that in reality are not uniformly opportunistic or equilibrium, and/or that

may differ for different life-stages. A more mechanistic demographic framework includes interactions among age-

specific mortality, density-dependent regulation, predation risk, as well as density-independent factors such as

extrinsic mortality, resource availability, and environmental fluctuations (Reznick, et al., 2002). A model of this

framework accounting for these many interactions for the Covered Species is not available.

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avoiding jeopardy. The pre-eminent dendrochronologist for the HCP area, Dr. Malcolm

Cleaveland, recently noted, “When you study the historic record [as revealed by tree-ring data],

you see there were multiple ten-year droughts worse than the so-called ’50s DOR. There was a

period in the 1500s and another in the late 1600s that make the 1950s look wet. You are going to

have at least one major drought every century if you study the data.” (Rivard, 2014).

In the long run, all of these factors are believed to work against an appreciable reduction in the

likelihood of survival and recovery of the Covered Species during the ITP term, which, as noted

at the beginning of this section, is one of the ITP issuance criteria.

5.3 Impact of Take on Covered Species Populations

5.3.1 Assessment of Population Impacts

This section summarizes the findings and conclusions of the District concerning take and

mortality, and assesses the consequences of take on the Covered Species populations. There is

considerable duplication of information presented in previous subsections and the appendices, as

this is intended to be a stand-alone section.

The Covered Species are subjected on a recurring basis to highly variable springflow, and during

periods of low flow, to naturally small DO concentrations that correlate directly with springflow

at the individual outlets. During such periods, data show the number of individuals observed

diminishes, which is likely due to a combination of mortality of individuals (population

reduction) and migration to areas in and near the spring outlets that are less accessible for

observation. The periods of low springflow during drought are followed by extended periods of

much-higher-than-average springflow and the rapid return of DO concentration to more normal

ranges. The epigean (surface-dwelling) Barton Springs salamander population increases

substantially during the flow-recovery periods after an apparent lag period of about six months.

The amount and rate of increase differ among the individual spring outlets and are also

dependent on the timing of droughts relative to one another (City of Austin, 2013). Rebound has

been significantly retarded after the most recent droughts at all outlets but especially at Old Mill

Spring. It is difficult to discern an overall trajectory with time for the robustness of the

population of either species; it varies naturally with the time step selected and drought

conditions, upon which groundwater withdrawals are superimposed. Some COA biological staff

have recently hypothesized that the salamander population(s) may have established a new,

smaller equilibrium, with a lower average size about which the population fluctuates more

restrictedly (City of Austin, 2013), as would be required if a population had more equilibrium

life-strategy characteristics rather than opportunistic life-strategy characteristics.

Responses of organisms to chemical stressors are inherently linked to the magnitude, frequency,

and duration with which organisms are exposed to the stressor(s) (Newman, 2009). While there

are other stressors for the Covered Species, as discussed in Section 3.2.2.2, Ecological Setting,

data indicate that DO stress associated with habitat modification represents the primary factor

that is specifically influenced by the District’s Covered Activities (Poteet and Woods, 2007). In

this HCP, because of their one-to-one correspondence, DO concentrations also serve as a

surrogate for the physical habitat that is provided by springflow and groundwater velocity. But

there is only a limited amount of protection with respect to DO for the Covered Species from

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regulatory institutions. In Texas, surface water quality standards are intended to protect aquatic

life and uses of surface-water bodies, and DO water quality criteria for high aquatic life use is

historically defined by either lotic (rivers and streams) or lentic (lakes and reservoirs) habitats

(Brooks et al., 2008). For example, a 24-hour DO-concentration minimum (3 mg/L) that does

not last longer than eight hours and a 24-hour minimum mean (5 mg/L) during a 24-hour period

is used for lentic systems (TCEQ, 2003). However, habitats supporting the Covered Species are

neither river nor lake, but aquifer, spring runs, and spring-fed pools. The current (2014)

understanding of the oxygen requirements of the Covered Species (Woods et al., 2010) does not

allow for a confident determination of whether existing DO criteria and standards are adequate to

protect these spring-fed habitats. Similarly, in spite of the innovative investigations and

management practices associated with the District’s HCP, the protections provided by the HCP

measures are also uncertain.

This is not an unusual circumstance. Environmental assessments of stressor-response

relationships for threatened and endangered species are consistently limited by lack of

experimental data for the covered species. In such cases, use of surrogate species is common

owing to limited availability of protected species. Because closely related species are not

necessarily common, the U.S. Environmental Protection Agency (USEPA) developed the Web-

based Interspecies Correlation Estimation (Web-ICE) to assist with such efforts

(http://www.epa.gov/ceampubl/fchain/webice/). Unfortunately, data for aquatic salamanders in

this software are not available, which prevented its application for the Covered Species. Further,

before initiation and development of this HCP, a quantitative understanding of DO stress on

Eurycea (including the Barton Springs and Austin blind salamanders) and other salamanders was

poorly understood. Thus, to assess the suitability of San Marcos salamander to serve as a

surrogate for Barton Springs salamander, a laboratory stressor-response study was done to define

metabolic rate relationships between Barton Springs and San Marcos salamanders (Woods et al.,

2010). Owing to these metabolic rate data and also genetic and life-history similarities between

those two species (Chippindale, et al., 2000), San Marcos salamander was selected as a surrogate

species for DO stressor-response studies of relevance to the Covered Species (Woods et al.,

2010). Use of this surrogate species for assessing take impacts on the Barton Springs salamander

in particular seems well founded.

Survival and growth responses to stressors have high relevance to the population level of

biological organization21 and are thus routinely used as measures of effect to support ecosystem

protection goals defined in ecological risk assessments (Suter, 2006). For DO, an adverse

outcome pathway (AOP) framework can be used to examine stress caused by hypoxia (low DO

concentration) and resulting impacts to individuals and populations of Covered Species (Figure

5-11). This AOP illustrates the large amount of information required to make confident

judgments of stressor-response impacts in real-world settings but which for the most part does

not exist for the Covered Species; at the same time, it indicates specific areas of additional

research.

21 Population (of a species) is one level in the hierarchy of biological matter, from simplest (atom) to most complex

(biosphere).

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To examine responses to DO concentration by a surrogate species, Woods et al. (2010) identified

mortality and growth DO thresholds during a 28-day study with adult and a 60-day study with

juvenile San Marcos salamander, respectively. As described in Section 5.2.1, Experimental

Assessment of Salamander Responses to Changes in Water Chemistry Related to Springflow, the

60-day NOAEL (No Observed Adverse Effect Level) for juvenile growth is 4.4 mg/L and the 28-

day LC5 estimate for adult mortality is 4.5 mg/L. (LC [Lethal Concentration]5 is the exposure

concentration in which 5% of the organisms die.) These thresholds from Woods et al (2010)

appear to represent the best data available for variable DO stress to these aquatic salamanders

(Dr. Bryan Brooks, personal communication, 2013)and thus provide a reasonable foundation for

interpreting DO risks of the Covered Activities to the Covered Species. Nevertheless, these

thresholds are the result only of controlled laboratory-based research investigations, not

extensive field investigations, which do not exist.

Figure 5-11: A proposed adverse outcome pathway (AOP) in the Covered Species for dissolved

oxygen. This AOP represents a conceptual model linking a molecular initiating event to adverse effects at higher levels of

biological organization. Source: Modified from Saari and Brooks (2013).

The scientific investigations and analyses done for this HCP indicate that salamander populations

are not adversely affected physiologically by DO concentrations of 4.5 mg/L or greater, and are

only mildly affected by DO concentrations slightly lower, at 4.2 mg/L. To be conservative, the

District has set a DO threshold of 5.0 mg/L, corresponding to a combined springflow of about 30

cfs, to represent conditions below which the salamander may begin to experience some

behavioral modifications. The salamander populations appear rather well-adapted to variability

in DO concentrations above this level (for example, Woods et al. (2010); White et al. (2006)).

Using available field and experimental data and inference, the lethal form of take is indicated to

begin for a small portion of the population at a springflow of about 20 cfs, which over the 97-

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year period of record would have occurred about 9% of the time even without any nonexempt

pumping (that is, without the Covered Activities). If DO concentration decreased to 3.9 mg/L

for an extended period, lethal take as individual salamander mortality could be noticeable and of

concern. If DO concentration decreased to less than 3.4 mg/L, the situation could be dire for

individual salamanders, and if prolonged without the mitigation proposed in this and the Barton

Springs Pool HCPs, dire for the population and recovery of the Covered Species. Given the

ecological setting and the population characteristics, take under the District HCP must be

inferred rather than directly observed, and the flow-duration relation (percentage of time

springflow is equaled or exceeded) for Barton Springs has been agreed by the Service to be a

rational proxy for DO concentration in assessing take in this HCP.

In addition to the physiological-related direct (e.g., metabolic changes in adult and juvenile

salamanders) and indirect (e.g., changes in predator-prey relationships) effects of DO reductions

on the Covered Species, another potential source of incidental take is the small reductions in the

wetted habitat area that might otherwise be attributable to the Covered Activities (“small”

especially relative to habitat reductions attributable to “natural drought” conditions). However,

the COA’s ongoing habitat restoration is just now being implemented, which precludes the

District from describing quantitatively the “new” wetted habitat; the new wetted habitat will

form a new baseline condition for the District’s HCP. Thus it is not possible to assess how

much, if any, of the new habitat could be changed by withdrawal-induced springflow reductions

at the reconfigured perennial springs during severe drought. These effects would likely be more

important to a dominantly density-dependent equilibrium species than to these species, where

habitat size is less of a concern than habitat conditions. As noted, the additional wetted habitat

and re-aeration provided by re-establishing the spring runs would also tend to offset any

concerns for the Covered Species arising from drought-induced wetted habitat loss, if any, at the

perennial spring outlets.

The measures now proposed under the HCP are more protective of springflow than any of the

previous alternative management scenarios, and they are believed to be the most protective that

can be applied under current law and with the current state of knowledge. Nevertheless, during a

recurrence of the DOR and under the District’s most stringent withdrawal-curtailment program,

springflows expressed in cfs will likely be in the mid-to-high single digits, which would be

unprecedented in the historical record. The DO concentrations of such springflows and the level

of salamander mortality and disruption of salamander life activities associated with a recurrence

of the DOR are unknown; but they probably would be appreciable without mitigation, which

underscores the importance of the proposed mitigation measures. The desired future condition

(DFC) of ensuring that springflow during a DOR recurrence is no less than 6.5 cfs (0.18 m3/s)

has been established by the District as its primary groundwater management objective,

representing a balance among various risks and uncertainties and also curtailments that are at the

maximum extent practicable. The proposed HCP conservation measures intended to minimize

and mitigate take and to avoid jeopardy are reasonably expected to achieve that objective.

There is much variability and uncertainty in this ecological system, as suggested by the AOP of

Figure 5-11 and as discussed next in Section 5.3.2, Uncertainties in Take and Impact

Evaluations. The variability and uncertainty preclude making conclusive determinations

regarding effects on organisms and impacts on populations on the basis of empirical observations

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of the Covered Species. Nevertheless, the District HCP implements management and

conservation measures based on sound science that are intended to reduce risks of DO stress to

the Covered Species, particularly risks associated with naturally occurring severe droughts.

5.3.2 Uncertainties in Take and Impact Evaluations

The estimates of take are considered useful approximations that are based on a number of

assumptions and stipulations to account for uncertainties. Many of the more important of these

uncertainties have been discussed in various preceding subsections. They and others are

summarized below, in no particular order, in one place in this document, to facilitate

identification and appreciation of their scope and significance to the take estimates and

ultimately the avoidance-of-jeopardy determination.

Effect of All Recharge Sources on Aquifer Water Level Declines

The groundwater modeling described in Section 3.2.2.1.2, Sources and Implications of Variation

in Springflow at Barton Springs, may not have explicitly included the effects of all significant

sources of groundwater recharge on the recession of Aquifer water levels during severe drought.

Recent information suggests that the 1:1 correspondence between withdrawals and springflow,

on which the springflow analysis in this HCP is based, may be less than 1:1 during severe

drought; that is, one unit of withdrawal might result in less than one unit of reduction in springflow. This uncertainty is conservative toward springflow and its calculated DO

concentrations, but the actual DO concentrations associated with declining water levels during severe drought are unknown.

Springflow Recurrence Frequencies for Other Than Monthly Means

The natural flows of Barton Springs as well as aggregate withdrawals change very slowly during

a prolonged, severe drought. Recurrence (nonexceedance) frequencies for monthly mean flows

would be very similar to weekly mean or even daily mean flows. As discussed in Section

3.2.2.1.2, Sources and Implications of Variation in Springflow at Barton Springs, actual flows

expressed as shorter than monthly flow durations would tend to decrease the percentage of time

flow is below a designated rate for the smaller durations because the changes would be derived

primarily from storms that, over short-term durations, increase springflow.

Likely Differences Between Authorized and Actual Pumpage by Permitted Groundwater

Users

The relationship between withdrawals and springflow that was modeled for the HCP was based

on use of the entire authorized amount each month by each permittee, which is a conservative

assumption in the HCP. Even though curtailments during drought are more likely to increase the

fraction of curtailed use represented by actual use, the District’s recent experience in drought

management indicates that actual use is still below the authorized curtailed use otherwise

permitted (Figure 3-9).

Springflow-related Factors Other Than DO Concentration

The District’s Covered Activities—that is, managed withdrawals from the Aquifer—can only

affect those physical and chemical habitat factors directly related to springflow. Of these, only

DO was modeled, inasmuch as the quantitative influence of other factors, other than temperature,

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has not been established. Temperature variations are controlled less by springflow and more by

seasonality or the number of high stormflows in springflow (Mahler and Bourgeais, 2013),

neither of which are controlled by the Covered Activities. Prolonged drought tends to reduce

temperature variation in springflow. Concentrations of ionic constituents do exhibit some

variation with springflow, but even the highest constituent concentrations are well within the

freshwater range and vary over a relatively narrow range of about 100 mg/L TDS (Herrington

and Hiers, 2010). Poteet and Woods (2007) examined the effects on adult salamanders over a

much wider range of salinity and found no behavioral response. No studies are known that

attribute physiological or behavioral changes to the small observed variations in salinity of

spring flows for either adult or non-adult life stages of the Covered Species.

Covered Species Population Size and Distribution

Because of their cryptic nature, spending an appreciable part of their time in subterranean or

otherwise inaccessible surface habitats, the population sizes of both Covered Species have not

been firmly established. This is especially pertinent to the Austin blind salamander, for which

only a small part of its Critical Habitat is observable.

For the Barton Springs salamander, the population sizes at the outlets are based on the mean-

plus-one SD metric that has been used in the COA’s approved Barton Springs Pool HCP for

estimating such take. For each outlet, their distribution will vary indeterminately with time and

water chemistry conditions.

The population size of the Austin blind salamander is simply unknown. It was inferred on the

basis of observed density of subterranean salamander species in surface environments in both

Barton and San Marcos Springs, adjustment for areal distribution of presumed habitat-supporting

conduits and fissures at the water table, and then extension to the Critical Habitat area. This

approach involves substantial uncertainty in the overall population size, as the incidental surface

density may not be representative of the subterranean density for such subterranean species and

its behavior in the subsurface is indeterminate within current science.

Another related assumption that was made for both species has to do with the DO concentrations

to which they are exposed and where those concentrations occur. The indicated DO

concentration at the spring outlets was applied to the entire existing populations for both species.

While other ecological factors, such as prey-predator relationships, substrate characteristics, and

water velocities come into play, the District believes that, other factors equal or not compelling,

an unknown but likely substantial fraction of the Barton Springs salamander population will tend

to move away from the surface outlet to water that has higher DO concentrations, although how

much higher is also unknown. The re-establishment of accessible spring runs (“daylighting”) at

the outlets of Eliza Spring and Old Mill Spring will, among other things, re-aerate the water and

provide a driving force for such migration. Similarly, an unknown but likely substantial fraction

of the Austin blind salamander population will either exist normally or move into the subsurface

away from the outlet once DO concentrations decrease to stressful levels, seeking subterranean

areas with a greater proportion of unconfined water that has higher DO concentrations. It is not

reasonable to assert that the entire population of either of these mobile species will continue to be

exposed to the same DO concentrations at the outlet when DO stress is high and less stressful

environments with higher DO concentrations are readily accessible to at least a portion of those

populations. A rather conservatively small amount of such DO relief is included in the analyses

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used in this HCP. The District considers it likely that salamander migration to areas of higher

DO concentration when under stress from low DO concentration may well be a primary

mechanism that has allowed these endemic species to have persisted through many and more-

severe droughts during their natural history. However, this tendency to migrate, its areal extent,

the proportion of the populations involved, and the degree of stress relief provided are all

unknown and presently indeterminate. These unknowns are likely the focus of future research.

Indirect Effects of Withdrawals on Other Species Important to the Covered Species

The take estimates in this HCP are based on habitat changes as they relate directly to the

Covered Species themselves, not on the macroinvertebrate community on which the salamanders

rely for prey (City of Austin, 2013). For example, the effect of depressed DO concentration at

low springflow on the size of and predator-avoidance behavior of the population of amphipod or

other prey in the habitat has not been evaluated. The District is unaware of a quantitative

relationship between springflow or DO concentration and the macroinvertebrate prey that could

be compared to the effects on the salamander species. In essence, the District is making an

assumption that the macroinvertebrates either are present in sufficiently large population

numbers that they are not a limiting factor for the salamanders, or they are not impacted

physiologically by low DO concentration to the same extent as the Covered Species, or both.

The validity of this assumption is unknown, but it introduces uncertainty that can only be judged

qualitatively. The COA has noted that some 100 taxa of macroinvertebrates have been

catalogued at the outlets, and while the abundance of the macroinvertebrate community

decreases with decreasing springflow, the decreases are not uniform across the entire community

(City of Austin, 2013). Such diversity would be beneficial to the predator Covered Species.

Furthermore, the Covered Species are known as invertevores, which means that they do not

discriminate as to what species of invertebrates become their prey, an adaptation that is

especially useful in energy production and conservation during drought. Nevertheless, the

relationship of springflow, DO concentration, and macroinvertebrate abundance and diversity

may be important to cumulative impacts and could be a worthwhile focus of future research,

although extreme low flows would be required for meaningful evaluation in the field.

Non-modeled Differences Between the Two Covered Species

Notwithstanding the differences in population sizes and their locations, for the most part the two

Covered Species are considered in the HCP analysis to react and behave similarly to differences

in DO concentrations, in absence of data to the contrary. However, the Austin blind salamander

is in a separate evolutionary branch from the Barton Springs salamander, and also the San

Marcos salamander that was used in the laboratory studies (City of Austin, 2013), so its

similarity in DO stress-response to the Barton Springs salamander is not assured. In fact, it

seems to spend a substantially greater part of its life in environments of naturally lower DO

concentration than the Barton Springs salamander in the near-field environs of the Barton

Springs complex; so it could be reasonably asserted that the Austin blind salamander might be

better adapted genetically to such environments. (The recent discovery of the Barton Springs

salamander, but not the Austin blind salamander at far-field locations remote from the Barton

Springs complex introduces additional uncertainty in such comparisons and conclusions.)

Because the existence, direction, and magnitude of differences in mortality relative to DO

concentration for the two species are indeterminate, no difference in the Austin blind

salamander’s mortality from that of the Barton Springs salamander is assumed in the modeling,

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which the District suggests may tend to overstate the Austin blind salamander’s mortality at a

given DO concentration. Other assertions could be made that no differences are known to exist

and that lack of data requires no difference to be imputed.

Lack of Data on DO Concentration Variations at Extreme Low Flows

The relationship between springflow and DO concentration was defined for each outlet by

regression equations based on paired observations of springflow and DO concentration at each

outlet. There were very few pairs with flow below 20 cfs (0.57 m3/s) and no pairs with flow

below 14 cfs (0.40 m3/s). Flows below 20 cfs constitute the zone of most interest to salamander

physiology and behavior. Relying solely on trends established by data at higher flows is

problematic and introduces additional uncertainty into the modeling.

Differences in DO Concentration Among Individual Spring Outlets

Whether and what trends actually exist between DO concentration and springflow and how they

differ among the outlets under extreme low-flow conditions is currently indeterminate, as

springflow has not been extremely low since DO measurements were begun. The markedly

different low-flow water chemistry observed at Old Mill Spring compared to that at Eliza and

especially Main Springs, along with its emergence along a different fault (Hauwert, 2009; Johns,

2006), suggest that Old Mill Spring might have a fundamentally different springflow-DO

concentration relationship. Old Mill Spring was modeled using the same type of regression

equation as the other two perennial outlets, even though the hydrogeologic setting could indicate

a different selection. Statistically, there is no basis to judge what regression relationship(s)

should be used (Porras, 2014; Turner, 2007).

Effect of DO Concentration Variations on Other Life Stages

Funding limitations required the laboratory study in this HCP to focus on the life stages of the

salamander typically encountered. Most of the stressor-response study addressed adult

salamander stages, with a limited investigation of DO stress to juveniles. Although adult stages

may be the lengthier stages and therefore adults are exposed to the largest variations in DO

concentration, the effect of DO-concentration variations on egg and larval forms is also

potentially important but unaccounted for in this HCP. However, no known data or studies

suggest that the Covered Species are especially susceptible to such variations of the magnitude

introduced by the Covered Activities. This may be an area for future research.

Differences Between Predicted and Observed DO Concentrations

The DO concentrations predicted by the regression equations on total springflow systematically

deviated from the DO concentrations actually measured for recent drought springflows by 0.6

mg/L, with the measured DO concentrations higher than those predicted (Turner, 2009). Some

of the deviation may be within the variability and error associated with statistical manipulations.

Porras (2014) indicates by statistical analysis that the variability and error may be on the order of

±0.2 mg/L. Some of the deviation might be from the use of one outlet for DO measurement but

all outlets in aggregate for developing the regression relationship; or simply from the

randomness and variability of any individual environmental event (in this instance, the 2008–09

drought). But generally, the deviation suggests that some of the uncertainties mentioned in this

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section, such as the absence of extreme low-flow DO data and regression relationships that are

consequently skewed, are in fact conservatively accommodated in the HCP; and that actual

effective DO concentration is higher than predicted and used in the take estimate.

Application of Laboratory Data to In-the-Field Conditions

Section 5.2.1.3, Implications and Limitations of Stressor-Response Study, discussed the

uncertainties in laboratory studies of natural biological systems, noting that the response of test

organisms under controlled conditions may not be the same as the response in the field.

Cumulative Risk Factors beyond the District’s Control

Adverse effects on the Covered Species resulting from anthropogenic water quality changes—for

example, nonpoint-source pollution arising from watershed modification—may be exacerbated

by or additive, synergistic, or antagonistic to adverse effects from springflow-related water

chemistry changes such as DO-concentration variations. These adverse effects may have

significant consequence to the Covered Species, but the District has no control over the existence

or magnitude of such factors, so those cumulative effects have not been considered in the take

estimate per se, in accordance with the Service’s guidance. Rather, the impacts of these sources

of additional risk are to be addressed in the environmental impact statement prepared by the

Service under the National Environmental Policy Act (NEPA) for this HCP.

The sources of uncertainty and variation discussed in this subsection notwithstanding, the

District is reasonably confident that the take estimates developed herein provide a relative sense

of the overall benefit of the proposed HCP conservation measures. On the basis of the recent

severe drought conditions, the District suggests that in aggregate the take estimates are

conservatively high. In practice, using these estimates is believed to provide a buffer of

additional protection.

5.3.3 Comparison with Take Impact Assessment in EARIP

The Final HCP for the San Antonio segment of the Aquifer by the Edwards Aquifer Recovery

Implementation Program (EARIP, 2012) covers a very large area and addresses many listed

species and many activities. It includes Eurycea salamander species that are quite similar to the

two Covered Species in this HCP; managed groundwater withdrawals are one of its Covered

Activities as in this HCP; and its HCP conservation measures are supported in part by the

groundwater regulatory program of one of its implementing parties (Edwards Aquifer Authority),

as is the District’s regulatory program in this HCP. The EARIP HCP was recently approved and

an ITP issued by the Service in 2013. Generally, the basis for the take impacts and for the

Service’s findings as to jeopardy related to the groundwater regulatory program in the EARIP

HCP and to those similar species should be consistent. In that regard, the similarities and

differences between the two HCPs are noted:

• The EARIP acknowledges the uncertainties associated with life requirements of its

salamander species in relation to springflow. In fact, it related the minimum flow

requirements for its salamander species to those of a listed plant species; and documented

that this flow requirement was supported by the rough approximations established by the

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Service in the early 1990s for gauging take and jeopardy for these salamander species at

Comal and San Marcos Springs. While these thresholds incorporated the best science then

available for evaluating take and jeopardy of the salamander species, the Service

acknowledged then that significant data gaps existed, requiring a more conservative approach

and the mandatory use of professional judgment to a greater degree than usual in setting the

take and jeopardy thresholds. However, even though substantially more information and

site-specific data exist today, the EARIP did not propose different thresholds for the listed

salamander species. The Service developed the original thresholds on a rather quick-

response basis as an outcome of federal litigation concerning groundwater regulation in the

San Antonio segment, and no analogous thresholds exist for the Barton Springs segment. In

their absence, and on the basis of data and science now available, this HCP proposes new

groundwater-management thresholds that are specifically designed to protect salamanders at

Barton Springs to the greatest extent practicable.

• The EARIP acknowledged that the indeterminate size of the actual total populations and the

uncertainties as to factors affecting their natural variability confounded quantitative take

estimates and impact analysis, necessitating use of assumptions and professional judgments.

This HCP does the same.

• The EARIP concluded that the uncertainty that existed about the impact of small springflows

of varying durations on the salamander species precluded definitive statements as to the

amount of take and its impacts. It essentially assumed that maintenance of continuous

springflow at least above the lower of the Service’s older, general thresholds (along with

protection of water quality from pollution) would enable the species to survive a repeat of

DOR-like conditions. This HCP expresses similar concerns about the uncertainties in

evaluating take and population impacts, even though using the new thresholds developed as

part of this HCP and evaluating adverse effects were informed by specific springflow-DO

concentration statistical relationships.

• The EARIP’s take analysis for these species primarily focused on physical habitat changes

and related effects caused by surface activities, which its participating entities can control. It

did not quantitatively evaluate hydrochemical effects, such as changes in DO concentration

and salinity, on salamander behavior and physiology related to springflow as is done in this

HCP, which is the only aspect that the District can control.

• The EARIP essentially assumed that the subterranean species would retreat into the Aquifer

even if springflow ceased and would generally not be adversely affected by small

springflows, although potential risk associated with take was assumed qualitatively to

increase at flows below the Service’s older lowest-flow threshold. This HCP reaches a

similar conclusion but supports it with a novel quantitative analysis of effects on organisms

over time and impacts on populations.

• The EARIP, which is designed to be a phased program, used a 15-year initial term for its

ITP, while this HCP is a non-phased program and proposes a 20-year term.

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• The EARIP included in its cumulative take analysis a seven-year DOR recurrence plus eight

“average” years for its ITP term. This HCP not only includes a seven-year DOR recurrence,

but also a seven-year Stage IV Exceptional Drought (the Hybrid Drought), plus six non-

drought years in its cumulative take analysis for the ITP term. Barton Springs is at a lower

elevation than any spring in the San Antonio segment of the Aquifer and thus is the regional

base outlet for the entire Edwards Aquifer, including the San Antonio segment; although

DOR springflows at Barton Springs are smaller, the recurrence interval of DOR springflows

at Barton Springs is likely longer (that is, smaller frequency of occurrence) than those at the

higher-elevation springs addressed by the EARIP.

• The EARIP asserted that the uncertainties associated with the qualitative analyses for these

species highlight the necessity of applied research, expanded biological and water quality

monitoring, and ecological modeling, and that those future developments will be factors in

assuring that the species are not jeopardized. This HCP does the same.

The analyses and assessments of the salamander species in both HCPs are best characterized as

qualitative, with quantitative approximations only and with some significant uncertainties that

are not readily accounted for or overcome. On the basis of the best science available and

reasonable assumptions and stipulations, both HCPs conclude that the proposed conservation

measures are necessary and sufficient to minimize take to the maximum extent practicable and to

avoid jeopardy.

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6.0 Conservation Program

The District is seeking a Section 10(a)(1)(B) Incidental Take Permit (ITP) to cover use of the

Aquifer as a water supply and management of the Aquifer by the District’s regulatory program

related to permitted withdrawals from the Aquifer (Covered Activities). Everything that the

District does relates to responsible groundwater use and to management of the aquifers in its

jurisdiction, including the Aquifer. By design, all District activities are intended to directly or

indirectly benefit the Aquifer and therefore the habitats of the Covered Species, especially

compared to the unregulated pumping conditions that would exist without the District’s

management efforts. So the Covered Activities integrate the conservation measures for the

Covered Species. However, these activities will not completely avoid or prevent take of the

species all the time, rather minimize and mitigate the take as it occurs, so the ITP is being sought

to accommodate those circumstances.

As a groundwater conservation district (GCD) in Texas, these activities are derived from and

authorized by inclusion in the District Management Plan (MP), and the District Rules. The

District cannot legally perform any activities, not even conservation activities, that are not

authorized by statute (Texas Water Code Chapter 36, or the District’s enabling legislation

codified as Special District Local Laws Code Chapter 8802) and also that are not at least

implicitly a part of the prevailing MP. The legal authority for the Rules & Bylaws (BSEACD,

2016) that compose the District’s regulatory program flows directly from the statutes under

which the District operates and from the MP.

The MP must be reviewed; revised as needed to accommodate new information, priorities, and

statutory requirements; re-adopted; and approved by the Texas Water Development Board

(TWDB) at least every five years. The current MP was recently revised and approved by the

TWDB on November 21, 2017. It will require review and re-adoption no later than September

2022. The current MP anticipates and includes the statutory-enabled regulatory authorities

needed for the set of the proposed District Habitat Conservation Plan (HCP) measures described

below; substantial changes to the HCP measures could necessitate an earlier-than-planned MP

revision and re-adoption. This duality in authorities illustrates that the measures committed to in

the HCP and the requirements of the MP are intertwined: Future revisions to the MP must honor

the commitments and requirements of the HCP once approved, and the HCP’s current measures

and future adaptive measures are restricted to those that are authorized by statute and by the

prevailing approved MP.

In addition, the District may carry out its statutory powers and responsibilities to amend rules

from time to time and substitute alternative requirements for reduction in withdrawals and/or

alternative practices, procedures, and methods for promoting increased groundwater levels. Such

rulemaking is an anticipated part of the District’s function as a regulatory agency. However, per

Service regulations on ITP holders, any such rule amendments made by the District must not

reduce the effectiveness of the restrictions on withdrawals described in the District HCP and

incorporated in the ITP to protect springflow. Otherwise, the District would be non-compliant

with its ITP, unless and until the HCP and ITP are also amended.

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6.1 Biological Goals and Objectives of HCP

The biological goals and objectives of the District HCP are established in recognition of (a) the

direct relationship between the volume of water in the Aquifer and the hydrochemistry of the

natural discharge from the Aquifer as springflow, and (b) the life requirements of the Covered

Species with respect to dissolved oxygen (DO) concentrations of the groundwater as it is

discharged from the Aquifer.

The biological goals of the District HCP are to:

Minimize drought-related decreases in size and health of the Barton Springs salamander

population to the maximum extent practicable, Minimize drought-related decreases in size and health of the Austin blind salamander

population to the maximum extent practicable, and

Promote recovery of the populations from those decreases to levels required for their long-

term viability.

The following objectives, derived from the impact analysis described in Section 5.2, support the

HCP in pursuit of those overarching goals:

1. Adopt and implement groundwater-management and HCP conservation measures to

avoid springflows that create anoxic conditions (DO concentration of 0.0 mg/L) at Main

Springs and Eliza Spring at all times;


minimize the a) spring area affected by, b) the deviation in DO concentrations below,

and c) the length of time that springflow-dependent DO concentrations at Main Springs

and Eliza Spring are less than 3.4 mg/L under all Aquifer conditions, including Extreme

Drought;


maintain combined springflows that correspond to monthly-average springflow-

dependent DO concentrations of no less than 4.0 mg/L at Main Springs and Eliza Spring

during all but Extreme Drought conditions; and

4. Adopt and implement groundwater-management and related measures that do not cause

other natural water chemistry parameters, as periodically monitored by the COA and

other governmental entities and reported to the District under terms of an Interlocal

Agreement, to exceed their historical ranges under all Aquifer conditions.

The first biological objective above is primarily an overarching and unequivocal statement of

intent to protect the existence of individual organisms of the Covered Species at Barton Springs,

regardless of the status of their overall populations, regardless of whether and how other

objectives are achieved, and regardless of hydrologic conditions.

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The second biological objectives is based on the LC50 value that was determined by laboratory

investigations in the course of developing this HCP (Poteet and Woods, 2007; Woods et al.,

2010). Its intent is to minimize the frequency and time-duration that the Covered Species would

be exposed to concentrations that present concerns about the long-term viability of the

populations. It refers to parameters only at Main and Eliza Springs because those are the only

outlets that will be flowing and able to be measured during Aquifer conditions that include

Extreme Drought.

The third objective is based on the results of recent field investigations and multi-variate

modeling of DO variations at the Barton Springs complex, especially at Main Springs, by the

USGS (Mahler and Bourgeais, 2013). Its intent is to restrict the amount of take to levels that the

populations of the Covered Species have already encountered during prior severe drought

periods. It refers to monthly-average conditions because the effects of groundwater management

and HCP conservation measures are not able to be measured more frequently than monthly as a

practical matter.

The fourth objective is designed to ensure that neither groundwater management nor mitigation

measures have unintended adverse consequences on the aquatic habitat of the Species. Its intent

is to account for and minimize those changes that could otherwise be introduced into these

natural systems by the groundwater management and HCP measures that could affect the

Covered Species or their habitats physically, hydrochemically, and/or biologically.

These objectives as they relate to managing groundwater withdrawals are believed to be

consistent with the best scientific information currently available and within the District’s

statutory authorities for groundwater management. Their implementation is integrated directly

into the operating conservation and management programs, policies, and rules of the District,

thus indicating a commitment to their achievement.

Specific measures to accomplish these objectives are discussed in detail in the following section.

These measures, both individually and in aggregate, represent the best attainable legal plan of the

District to conserve the species and are designed to correspond with the scope of the HCP. The

District believes these measures substantially improve the probabilities that all of these

objectives are achieved throughout the life of the ITP.

6.2 Minimization and Mitigation Measures

The key to conserving and minimizing take of the Covered Species is maintenance of adequate

habitat and ambient conditions to provide the necessary life requirements for the species. This

goal can be accomplished (1) if external factors beyond the District’s control (for example,

substantial increases in oxygen-demanding material from point-source and nonpoint-source

pollutants in runoff) do not determine habitat quality, (2) if the measures in the COA’s HCP for

Barton Springs Pool afford the designed protection during recreational use and maintenance of

the pool, and (3) if the management of the Aquifer as proposed in this District HCP protects and

maintains springflow sufficient to provide minimum acceptable habitat consistent with those life

requirements.

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As mentioned previously, the nature of the Covered Activities is inconsistent with the avoidance

of take in an absolute sense. However, the minimization and mitigation measures that have been

established by the District reduce groundwater withdrawals during the key Extreme Drought

period to an amount that is about the same as existed when the District was formed and when an

unfettered, vested property right attached to such withdrawals (about 5 cfs, or 0.14 m3/s), as

described in Section 4.1.2, Historical Perspective of Covered Activities). In this sense, the

District’s groundwater management program proposed herein not only minimizes take during all

drought conditions, but during the most critical period for the Covered Species, avoids the take

associated with all withdrawals begun after the District was established and its regulatory

program began.

6.2.1 Direct HCP Measures

The conservation measures that the District is committing to undertake under the HCP to

conserve the Covered Species, by avoiding or minimizing take to the greatest extent possible, are

identified and discussed in this section of the HCP. The next section, 6.2.2, Other HCP

Measures and Strategies, addresses the mitigation measures and the complementary research

program that the District is committing to undertake under prescribed conditions. The funding

and management metrics are further described in Chapter 8, District Funding Assurances, and in

the District’s current 2017 MP, respectively.

Because the direct measures are also integral to the District as an operating GCD, they are

discussed in categories that correspond with the overarching statutory goals for all GCDs in

Texas. The numerical order of these goals in the subsections below conforms to their listing in

statute, not in the order of importance to the HCP. These measures are now District-specific

objectives or performance standards in the District’s most recently approved November 2017MP,

and as such are legal commitments of and by the District. (For a few measures, this HCP

provides slightly revised wording for clarity purposes, without altering the meaning or intent of

the authorizing MP measures.) Taken together, these measures compose the “Enhanced Best

Attainable Alternative” for the HCP that is the embodiment of the District’s own, internal

adaptive management process, as discussed in section 6.4, District HCP Adaptive Management

Process.

All of these measures are currently authorized and are either underway or, for a few, will be

initiated as of the issuance of the ITP. As such, they embody the commitment of the District to

the HCP. They include both ongoing (currently authorized and continuously operating, as

warranted) and episodic avoidance/minimization measures, as specified in the following

descriptions. All measures described as “ongoing” measures should be considered to be

“initiated and continuing” ones as of the date of ITP issuance. All regulatory-related measures

are or will be subject to enforcement by the District, as described further in Section 6.5.1.4,

District Enforcement Program. By design and as required by law, these measures provide a

necessary balance between maximizing the amount of groundwater available for use and

conserving and protecting the groundwater resource, including Covered Species protection.

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During the 20-year term of the ITP, it is envisioned that some changes to these measures will be

required or prudent, but unless the underlying ITP permit is amended, the effect of any changes

to the measures will be at least as, if not more, protective of the Covered Species by reducing

attendant incidental take.

The following subsections describe the direct conservation measures proposed by the District in

its HCP. Each measure has a corresponding objective and one or more associated performance

standards (metrics) set forth in the prevailing MP, which is reviewed and revised every five

years by statute, to be responsive to all then-recognized needs. The current (2017) MP

incorporates the HCP direct measures as objectives or, for a few, as performance standards,

which authorizes and requires their implementation. It is accessible at:

http://bseacd.org/uploads/MGMTPLAN.TWDBApproved112117_reduced.pdf. The staff

formally documents and assesses compliance with the applicable performance standards of the

MP annually. This evaluation in turn informs a separate annual assessment by the District’s

Board of Directors that is focused on the MP objectives and HCP measures and ultimately on the

overall progress toward the planned goals, all of which become part of the public record. These

also will be incorporated into the annual reports to the Service (the District’s prospective federal-

level regulatory authority) and to TCEQ (the District’s state-level regulatory authority), as

described in Section 6.5.1.1, Administration and Reporting. The annual reports are intended to

serve as the primary tracking method for measuring performance and progress towards achieving

the MP’s and HCP’s goals and objectives. Other, more indirect conservation initiatives,

including mitigation measures and research areas, are identified and discussed in the Section

6.2.2, Other HCP Measures and Strategies. Section 6.2.3, Summary of HCP Measures to

Minimize and Mitigate Take, contains a synopsis of the HCP program, including a summary

table of HCP commitments that shows the correspondence between the HCP measures and the

Management Plan’s performance standards and metrics.

6.2.1.1 Providing Most Efficient Use of Groundwater

This goal encompasses actions that assure the relevant statutory, regulatory, scientific,

administrative, and education dimensions of the District programs promote a balance between

the least consumption of groundwater for each type of use and the benefits of using groundwater

for those uses. Such efficiency optimizes using groundwater as a water supply and preserving,

conserving, and protecting the groundwater resources for future uses, including endangered

species habitat. Therefore, all measures under this goal are ongoing Minimization Measures

except 1-3, which is chiefly an adaptive prelude to adjusted minimization.

• HCP Measure 1-1: Provide and maintain on an ongoing basis a sound statutory, regulatory,

financial, and policy framework for continued District operations and programmatic needs.

• HCP Measure 1-2: Monitor aggregated use of various types of water wells in the District, as

feasible and appropriate, to assess overall groundwater use and trends on a continuing basis.

• HCP Measure 1-3: Evaluate quantitatively at least every 5 years the amount of groundwater

withdrawn by exempt wells in the District to ensure an accurate accounting of total

withdrawals in a water budget that includes both regulated and non-regulated withdrawals, so

that appropriate groundwater management actions are taken.

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• HCP Measure 1-4: Develop and maintain programs that inform and educate citizens of all

ages about groundwater and springflow-related matters, which affect both water supplies and

salamander ecology.

6.2.1.2 Controlling and Preventing Waste of Groundwater

This goal encompasses functions related to ensuring that all groundwater that is withdrawn from

wells is used beneficially, and that activities that may cause or contribute to wasteful use of

groundwater and to the pollution or harmful alteration of the groundwater resource are

prevented. Only reasonable demand for beneficial use can be authorized through the permitting

process, and no well is allowed to waste groundwater, including allowing the commingling of

poor-quality and high-quality groundwater. For the HCP, measures under this goal minimize the

amount of groundwater withdrawn without purpose or reasonable use and that allows subsurface

deterioration of the reservoir, and thereby maximizes high-quality springflow for salamander

habitat. Therefore, all measures under this goal are ongoing Minimization Measures.

• HCP Measure 2-1: Require all newly drilled exempt and nonexempt wells and all plugged

wells to be registered and to comply with applicable District Rules, including Well

Construction Standards.

• HCP Measure 2-2: Ensure permitted wells and well systems are operated as intended by

requiring reporting of periodic meter readings, making periodic inspections of wells, and

reviewing pumpage compliance at regular intervals that are meaningful with respect to the

existing aquifer conditions.

6.2.1.3 Addressing Conjunctive Surface Water Management Issues

This goal promotes measures and policies that use joint surface water-groundwater systems

effectively, without imposition of adverse quantity or quality impacts on either the surface or

groundwater resource. In the context of the HCP, conjunctive use is alternative water use in lieu

of using the fully subscribed Edwards resource as a water supply and that allows for needed

pumpage curtailments, especially during Extreme Drought. Generally, these measures are

supporting measures for other, more direct HCP measures. To the extent the District is able to

undertake certain of these activities directly, either on its own or as part of a partnership, it may

provide a potential model or framework by which its permittees could also undertake such

actions.

• HCP Measure 3-1: Assess the physical and institutional availability of existing regional

surface-water and alternative groundwater supplies and the feasibility of those sources as

viable supplemental or substitute supplies for District groundwater users. This is an ongoing

Minimization Measure that is an adaptive prelude to a Research Measure and possibly a

Mitigation Measure.

• HCP Measure 3-2: Encourage and assist District permittees to diversify their water supplies

by assessing the feasibility of alternative water supplies and fostering arrangements with

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currently available alternative water suppliers. This generally is an ongoing Minimization

Measure, but depending on the specific arrangements pursued, it could also be an episodic

Minimization Measure.

• HCP Measure 3-3: Demonstrate the importance of the relationship between surface water and

groundwater, and the need for implementing prudent conjunctive use through educational

programs with permittees and public outreach programs. This is an ongoing Minimization

Measure.

6.2.1.4 Addressing Natural Resource Management Issues

This goal focuses on protecting the natural resources of the Aquifer and of other aquifers within

the District’s jurisdiction, including not only the groundwater of those aquifers but also soils and

agriculture; air quality; economic resources such as sand and gravel and oil and gas; and the flora

and fauna dependent on them, including endangered species. By using sound science to increase

the understanding of the natural resource systems, including relationships with underlying and

overlying water-bearing rocks and up-gradient surface waters, and to delineate the impacts

associated with the amount and location of pumping, recharge, and discharge, appropriate and

acceptable policies and rules can be developed and effective regulatory decisions can be made by

the District.

• HCP Measure 4-1: Assess ambient conditions in District aquifers on a recurring basis by (1)

sampling and collecting groundwater data from selected wells and springs monthly, (2)

conducting scientific investigations as indicated by new data and models to better determine

groundwater availability for the District aquifers; and (3) conducting studies as warranted to

help increase understanding of the Aquifer and, to the extent feasible, detect possible threats

to water quality and evaluate their consequences. This is an ongoing Minimization Measure

that is also an adaptive prelude to a Research Measure and possibly a Mitigation Measure.

• HCP Measure 4-2: Evaluate site-specific hydrogeologic data from applicable production

permits to assess potential impact of withdrawals to groundwater quantity and quality, public

health and welfare, contribution to waste, and unreasonable well interference. This is an

ongoing Minimization Measure.

• HCP Measure 4-3: Implement separate management zones and, as warranted, different

management strategies to address more effectively the groundwater management needs for

the various aquifers in the District, particularly the Aquifer. This is an ongoing Minimization

Measure.

• HCP Measure 4-4: Actively participate (with other GCDs in GMAs 9 and 10) in the joint

planning processes for the relevant aquifers in the District to establish and refine Desired

Future Conditions (DFCs) that protect the Aquifer and other aquifers and the Covered

Species. This is an ongoing Minimization Measure that is an adaptive prelude to an episodic

Minimization Measure.

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6.2.1.5 Addressing Drought Conditions

This goal involves developing and implementing policies that effectively manage groundwater

drought conditions in the Aquifer. The regulation of withdrawals and their curtailment during

drought, especially during prolonged severe drought, is the principal institutional minimization

tool that allows the otherwise lawful pumping of the Aquifer to occur while being protective of

the Covered Species. For example, now the only permits available to withdraw water from the

Aquifer are Conditional Production Permits, which is an interruptible supply that is subject to

complete cessation of pumping during drought and is issued only if an alternative supply is

available. All these are ongoing Minimization Measures, although during severe drought, the

step-wise implementation of increasingly stringent curtailments of water withdrawals could also

be considered episodic Minimization Measures; over time they also would inform an adaptive

outcome.

• HCP Measure 5-1: Adopt and keep updated a science-based drought trigger methodology and

frequently monitor drought stages for the Aquifer on the basis of actual aquifer conditions,

and declare drought conditions as determined by analyzing data from the District’s defined

drought triggers and from existing and such other, new drought-declaration factors,

especially the prevailing DO concentration trends at the spring outlets, as warranted.

• HCP Measure 5-2: Implement a drought management program that step-wise curtails Aquifer

use to at least 50% by volume of authorized aggregate monthly use in 2014 during Extreme

Drought, and that designs/uses other programs that provide an incentive for additional

curtailments where possible (for example, cap-and-retire of historical production permits;

accelerated and/or larger severe drought curtailments in exchange for additional authorized

use during non-drought periods).

• HCP Measure 5-3: Inform and educate permittees and other Edwards Aquifer well owners

about the significance of declared drought stages and the severity of drought and encourage

practices and behaviors that reduce water use by a stage-appropriate amount.

• HCP Measure 5-4: Assist and, where feasible, incentivize individual historical-production

permittees in developing drought planning strategies that foster compliance with

implemented District drought rules, including step-wise demand curtailment by drought stage

to at least 50% of currently (2014) authorized use, on a three-month rolling average basis,

during Extreme Drought; “right-sizing” authorized use over the long term to reconcile actual

water demands and permitted levels; and as necessary and with appropriate conditions, the

substitution by surface water, reclaimed water, and/or other groundwater resources such as

the Trinity Aquifer to achieve curtailments.

• HCP Measure 5-5: Implement a Conservation Permit that is held by the District and

accumulates and preserves water in the Aquifer that was previously authorized for

withdrawal as historic-use and that are retired or otherwise additionally curtailed during

severe drought, for use as ecological flow at Barton Springs during Extreme Drought and

thereby increase springflow for a given set of hydrologic conditions.

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6.2.1.6 Addressing Demand Reduction through Conservation

This goal encompasses all activities that strive to reduce consumption of groundwater of the

Aquifer by educating District stakeholders about water conservation and extraordinary demand-

reduction measures. This initiative provides tools by which all end-users of the Aquifer can

preserve springflow and the quality of habitat of the Covered Species, as well as Aquifer water

levels in wells, by reducing per-capita water use during non-drought periods as well as

episodically during severe drought. These are primarily ongoing Minimization Measures once

developed, although the temporary demand reductions during drought that are enabled here have

an episodic Minimization aspect as well.

• HCP Measure 6-1: Develop and maintain programs that inform, educate, and support District

permittees in their efforts to educate their end-user customers about water conservation and

its benefits, and about drought-period temporary demand reduction measures.

• HCP Measure 6-2: Encourage use of conservation-oriented rate structures by water utility

permittees to discourage egregious water demand by individual end-users during declared

drought.

• HCP Measure 6-3: Develop and maintain programs that educate and inform District

groundwater users and constituents of all ages about water conservation practices and

resources.

6.2.1.7 Addressing Supply through Structural Enhancement

This goal encompasses various structural activities—typically, engineered solutions that are

undertaken by the District directly to increase the amount of water in the Aquifer over that which

would otherwise be available. By increasing the water in storage and by providing means to

increase supply, either at all times or during certain times, impacts of drought can be less

frequent, less severe, and of shorter duration, springflows can be preserved, and endangered-

species habitat impairment can be minimized. These are generally adaptive preludes to

Mitigation Measures and the research program, as the ability to implement them varies with

knowledge and with time; but to the extent they are used, they have as well either ongoing or

episodic Minimization dimensions, or both.

• HCP Measure 7-1: Improve recharge to the Aquifer by conducting studies and, as

engineering feasibility is established and as allowed by law22, physically altering (cleaning,

enlarging, protecting, diverting surface water to) discrete recharge features that will lead to

an increase in recharge and water in aquifer storage beyond what otherwise would exist

naturally.

22 Certain enhanced-recharge activities in the Edwards Aquifer are governed by TCEQ under the Injection Well

Control Program. Further, certain parts of the ITP Area are within the Water Quality Protection Lands program of

the City of Austin, which must approve any recharge enhancement activities conducted by others in those areas.

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• HCP Measure 7-2: Conduct technical investigations and, as engineering feasibility is

established, assist water-supply providers in implementing engineered enhancements to

regional supply strategies, including desalination, aquifer storage and recovery, and effluent

reclamation and re-use, to increase the options for water-supply substitution and reduce

dependence on the Aquifer.

6.2.1.8 Quantitatively Addressing Established Desired Future Conditions

This goal involves supporting, monitoring, and keeping updated the currently adopted DFCs for

the Aquifer that protect water-well yields in the more vulnerable parts of the Aquifer and protect

springflow, and consequently of the Covered Species. The DFCs for the Aquifer provide the

statutory and regulatory basis, in the consensus of all GCDs in the State’s Groundwater

Management Area (GMA)10, for mandatory curtailments of withdrawals and aggregated firm-

yield caps on withdrawals and increases in recharge so that the DFCs are achieved. The DFCs to

protect well yields and springflow are considered the most important HCP measures, and all the

others are supportive of these two measures; the DFCs are also continuing adaptive management

measures, as they are statutorily iterative and re-adopted at least every five years. Achieving

these two measures is the principal metric for gauging success of the District’s groundwater

management program and HCP.

• HCP Measure 8-1: Adopt rules that restrict, to the greatest extent practicable, the total

amount of groundwater authorized to be withdrawn annually from the Aquifer to an amount

that will not substantially accelerate (i.e., by no more than one month, as stipulated by the

District’s Board of Directors) the onset of drought conditions in the Aquifer; this is

established and will be monitored as a running seven-year average springflow at Barton

Springs of no less than 49.7 cfs (1.41 m3/s) during average recharge conditions. This is an

ongoing Minimization Measure.

• HCP Measure 8-2: Adopt rules that restrict, to the greatest extent practicable and as legally

possible, the total amount of groundwater withdrawn monthly from the Aquifer during

Extreme Drought conditions in order to minimize take and avoid jeopardy of the Covered

Species as a result of the Covered Activities, as established by the best science available.

This is established as a limitation on actual withdrawals from the Aquifer to a total of no

more than 5.2 cfs (0.15 m3/s) on an average annual (curtailed) basis during Extreme Drought,

which will produce a minimum springflow of not less than 6.5 cfs (0.18 m3/s) during a

recurrence of the drought of record (DOR). This is a currently established episodic

Minimization Measure that operates during the most severe stage of drought when the

Covered Species are under highest stress.

6.2.2 Other HCP Measures and Strategies, Including Mitigation

As a complement to the direct HCP measures identified above, the District is also committing to

certain other measures and strategies to mitigate consequences on the Covered Species of

groundwater use in the District’s jurisdiction. The District is committing to pursue a focused

research program as an additional strategy under the HCP. These other measures and strategies

are collectively termed “indirect HCP measures” in this HCP.

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To a substantial extent, these indirect measures require involvement of other parties in addition

to the District. Such measures will be further defined and undertaken through available and

appropriate mechanisms, which may include grant funding, other external funding, in-kind

contributions, partnerships, and negotiation of requisite interlocal and other agreements. In

particular, the prospective interlocal agreement (ILA) with the COA, which both the COA and

the District have committed to establish under their respective ITPs and HCPs, offers strategic

benefits to the District in applying these indirect HCP measures in multiple ways. Some of these

indirect measures may be continuing commitments of in-kind and other resources for a specified

beneficial purpose, and others may be participating in various ways for special-purpose projects

that are authorized by the HCP but will be subject to future Board approval of scope, funding

sources and amounts, and opportunity costs. Although to a considerable extent these indirect

measures are HCP-specific, they leverage existing information from other parties and avoid

redundant efforts, are consistent with the District’s charge to expand the knowledge of the

Aquifer, and are beneficial to the District’s permittees in helping to acquire a legal shield against

assertions of violating the Endangered Species Act (Act).

The currently anticipated implementation schedule and a summary of the types and level of

effort and their currently planned aggregated costs are provided as part of the description of each

of these indirect HCP measures. In any one year, these costs are likely to include some variable

combination of cash contributions, in-kind labor, and contracted support. The costs associated

with them are a part of the overall funding commitment described in Chapter 8, District HCP

Funding Assurances.

6.2.2.1 Research

Substantial uncertainties exist concerning a number of factors that at least potentially affect take:

the hydrologic performance of the Aquifer, especially during extreme low-flow conditions; the

relationship between springflow and its DO concentrations, especially during extreme low-flow

conditions; the ecological effects and physiological impacts of antagonistic contaminants in

recharge water; and salamander behavior, both individually and as a population, under ecological

stress.

The District is committing to a research program to address some of these uncertainties as an

HCP strategy. That research will inform the HCP’s Adaptive Management Program (AMP) and

the proposed research is described in more detail in Section 6.4.1, Research Supporting the

AMP.

6.2.2.2 Mitigation Measures

The District recognizes that the proposed conservation program is unable to avoid take at all

times. Consequently, it commits to the following Mitigation Measures:

• HCP Mitigation Measure M-1: The District commits to supporting the operations of an

existing refugium with facilities capable of maintaining backup populations of the Covered

Species to preserve the capacity to re-establish the species in the event of the loss of

population due to a catastrophic event such as an unexpected cessation of springflow or a

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hazardous materials spill that decimates the species habitat. Such supplemental support

would be provided through a commitment of in-kind, contracted support, and/or cash

contributions or other appropriate means of support that would contribute to:

1. Continuing the study of salamander physiology and/or behavior, and/or

2. Conserving field and captive populations.

Commitments of in-kind, contracted support, and/or cash contributions to support the

refugium and its research program may be specified by the Board.

Measure M-1 will be supported on a recurring three-year cycle throughout the term of the

ITP and beginning in the first three years, as to be agreed upon in the MOU/ILA. The

District is currently planning to commit cash contributions, in-kind labor, and contracted

support in an aggregate amount of $40,000 to this measure over the ITP term.

• HCP Mitigation Measure M-2: The District, in cooperation with the COA, commits to

participating in conducting feasibility studies and, as warranted, pilot and implementation

projects to evaluate the potential for beneficial subsurface DO augmentation and improved

surface DO augmentation in the outlets (only) of the Aquifer during Extreme Drought

conditions. This measure will involve assessing and utilizing injection of oxygenated or

aerated water into the Aquifer through the monitor well installed as part of the Research

Measure R-1, and/or improving devices and methods for aerating subsurface water in the

immediate vicinity of the outlets. In-kind, contracted support, and/or cash contributions,

phased during the term of the permit, may be authorized for feasibility studies and, if a

project is feasible, for the pilot study and implementation of the augmentation project.

Measure M-2 will be informed by the results of Measure R-1 and will be authorized and

specified in the to-be-negotiated MOU/ILA with the COA. This is a critical mitigation

measure, and the District will strive to have it operational as soon after ITP issuance as

possible. But by necessity, to avoid potential take that could be associated with this measure,

the subsurface augmentation project will need to be conducted in a phased fashion, beginning

with a feasibility study, to be initiated no later than Year 2 and completed no later than Year

5, and, if the study indicates it is feasible, continuing through a pilot study and full

implementation, to be complete no later than Year 12. The level of effort will be higher in

the earlier years of this 8-year implementation period. The District is currently planning to

commit cash contributions, in-kind labor, and contracted support in an aggregate amount of

up to $147,000 to this measure over the ITP term.

• HCP Mitigation Measure M-3: The District commits to extending the time period to maintain

and operate the Antioch Recharge Enhancement Facility for the term of the ITP, thereby

improving recharge water quality and reducing nonpoint-source pollution at the outlets from

runoff during that time. This will include maintaining the existing equipment, replacing

damaged equipment, and purchasing better quality equipment.

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Measure M-3 will be implemented by the District beginning the first year of the ITP and then

continuing every year of the ITP term; a recurring three-year cycle is anticipated for its level

of effort. The District is currently planning to commit cash contributions, in-kind labor, and

contracted support in an aggregate amount of $289,000 to this measure over the ITP term.

• HCP Mitigation Measure M-4: The District commits to establishing a new reserve fund for

plugging abandoned wells to eliminate high-risk abandoned wells as potential conduits for

contaminants from the surface or adjacent formations into the aquifer, with priority given to

problematic wells close to the Barton Springs outlets and/or associated with water chemistry

concerns under severe drought conditions. This reserve fund, which like others under state

law has restrictions on its funding and use, would be established within the first year after

issuance of the ITP by closing the existing Drought Reserve Account, whose stipulated

purpose has been legal defense for drought management, and then by utilizing its current

balance to initially fund a new Aquifer Protection Reserve Account. The new account would

exist solely to fund plugging of abandoned wells and would be replenished after the first year

with any collected enforcement penalties, any drought management fees imposed on larger

nonexempt permittees that do not meet their drought curtailments, and an annual budgeted

supplement at the discretion of the Board. Plugging wells is a relatively expensive activity

and each requires advance planning and negotiation with the well owner.

Measure M-4 will be initiated in Year 1 of the ITP and will continue annually throughout the

ITP term, with a roughly 5-year cycle for its level of effort. The District is currently

planning to commit cash contributions, in-kind labor, and contracted support in an aggregate

amount of $412,000 to this measure over the ITP term.

• HCP Mitigation Measure M-5: For the term of the ITP, the District commits to provide

leadership and technical assistance to other government entities, organizations, and

individuals when prospective land-use and groundwater management activities in those

entities’ purview will, in the District’s assessment, significantly affect the quantity or quality

of groundwater in the Aquifer. The District will respond actively and appropriately to

legislative initiatives or projects that affect Aquifer characteristics, provided such actions are

consistent with established District rules, ongoing initiatives, or existing agreements.

(Examples include contesting unsustainable wastewater management or actions that

contravene the District’s consent decree(s) that are projected to adversely affect the Aquifer,

and providing technical support to GMA 9 and other GCDs whose practices may affect the

Aquifer.)

Measure M-5 activities are typically multi-year initiatives, and the District will establish a

baseline in both the intensity of District involvement and the number of initiatives to be

undertaken during the first 5 years and then continue annually on a roughly 5-year cycle for

its level of effort. The District is currently planning to commit cash contributions, in-kind

labor, and contracted support in an aggregate amount of $328,000 to this measure over the

ITP term. This support is primarily a combination of senior District staff labor and legal and

lobbying support expenses.

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6.2.3 Summary of HCP Measures to Minimize and Mitigate Take

A summary of all the direct and indirect measures that constitute the core commitments of the

District HCP is presented in Table 6-1. Taken together, these measures lay out the District’s

preferred option for the HCP Conservation Measures proposed in this HCP. In addition, the

table specifies the applicable performance standard(s) from the District’s approved 2017 MP as

they correspond to each measure. The objectives and performance standards essentially

authorize the District to perform that HCP measure, and the performance standards set forth how

success in executing the measures and achieving the objectives will be assessed and reported.

These objectives and performance standards provide demonstration of the District’s commitment

to fund and implement each of the HCP conservation measures as integral component of its

ongoing operations. The current MP, which is revised as necessary and re-approved by the

TWDB at least every five years, is on the District website, at: http://www.bseacd.org/about-

us/governing-documents/.

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Table 6-1: Summary of HCP Measures and correspondence with Management Plan objectives and performance standards

Plan Objectives and Performance Standards Showing Correspondence between Management Plan and Habitat Conservation Plan

Lead Team Color Coding:

General Management

Administration

Education & Outreach

Aquifer Science

Regulatory Compliance

GOAL 1 - Providing the Most Efficient Use of Groundwater – 31TAC356.52(a)(1)(A)/TWC §36.1071(a)(1)

HCP Measures – Providing Most Efficient Use of Groundwater MP ID No.

2017 Management Plan

Objectives

2017 Performance Standards

HCP ID No.

2013 MP Standard*

1-1 Provide and maintain on an ongoing basis a sound statutory, regulatory, financial, and policy framework for continued District operations and programmatic needs.

A. Develop, implement, and revise as necessary, the District Management Plan in accordance with state law and requirements. Each year, the Board will evaluate progress towards satisfying the District goals. A summary of the Board evaluation and any updates or revisions to the management plan will be provided in the Annual Report.

B. Review and modify District Rules as warranted to provide and maintain a sound statutory basis for continued District operations and to ensure consistency with both District authority and programmatic needs. A summary of any rule amendments adopted in the previous fiscal year will be included in the Annual Report.

1-1 PS 1-1, PS 1-2, PS 2-1

1-2 Monitor aggregated use of various types of water wells in the District, as feasible and appropriate, to assess overall groundwater use and trends on a continuing basis.

Monitor annual withdrawals from all nonexempt wells through required monthly or annual meter reports to ensure that groundwater is used as efficiently as possible for beneficial use. A summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type will be provided in the Annual Report.

1-2 PS 2-3, PS 2-4, PS 3-1, PS 6-1, PS 6-2

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1-3 Evaluate quantitatively at least every five years the amount of groundwater withdrawn by exempt wells in the District to ensure an accurate accounting of total withdrawals in a water budget that includes both regulated and non-regulated withdrawals, so that appropriate groundwater management actions are taken.

A. Provide an estimate of groundwater withdrawn by exempt wells in the District using TDLR and TWDB databases and District well records and update the estimate every five years with the District’s management plan updates.

B. In the interim years between management plan updates, the most current estimates of exempt well withdrawals will be included in a summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type that will be provided in the Annual Report.

1-3 PS 4-2

1-4 Develop and maintain programs that inform and educate citizens of all ages about groundwater and spring flow-related matters, which affect both water supplies and salamander ecology.

A. Publicize District drought trigger status (Barton Springs 10-day average discharge and Lovelady Monitor Well water level) in monthly eNews bulletins and continuously on the District website.

B. Provide summaries of associated outreach and education programs, events, workshops, and meetings in the monthly team activity reports in the publicly-available Board backup.

C. A summary of outreach activities and estimated reach will be provided in the Annual Report.

1-4 PS 3-3, PS 4-4

1-5 Ensure responsible and effective management of District finances such that the District has the near-term and long-term financial means to support its mission.

A. Receive a clean financial audit each year. A copy of the auditor’s report will be included in the Annual Report.

B. Timely develop and approve fiscal-year budgets and amendments. The dates for public hearings and Board approval of the budget and any amendments will be provided in the Annual Report.

N/A PS 1-3

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1-6 Provide efficient administrative support and infrastructure, such that District operations are executed reliably and accurately, meet staff and local stakeholder needs, and conform to District policies and with federal and state requirements.

A. Maintain, retain, and control all District records in accordance with the Texas State Library and Archives Commission-approved District Records Retention Schedule to allow for safekeeping and efficient retrieval of any and all records, and annually audit records for effective management of use, maintenance, retention, preservation and disposal of the records’ life cycle as required by the Local Government Code. A summary of records requests received under the PIA, any training provided to staff or directors, or any claims of violation of the Public Information Act will be provided in the Annual Report.

B. Develop, post, and distribute District Board agendas, meeting materials, and backup documentation in a timely and required manner; post select documents on the District website, and maintain official records, files, and minutes of Board meetings appropriately. A summary of training provided to staff or directors or any claims of violation of the Open Meetings Act will be provided in the Annual Report.

N/A PS 1-4

1-7 Manage and coordinate electoral process for Board members.

Ensure elections process is conducted and documented in accordance with applicable requirements and timelines. Elections documents will be maintained on file and a summary of elections-related dates and activities will be provided in the Annual Report for years when elections occur.

N/A PS 1-5

GOAL 2 - Controlling and Preventing Waste of Groundwater – 31TAC 356.52(a)(1)(B)/TWC §36.1071(a)(2)) HCP Measures – Controlling and Preventing Waste of Groundwater

MP ID No.

2017 Management Plan Objectives

2017 Performance Standards HCP ID No.

2013 MP Standard*

2-1 Require all newly drilled exempt and nonexempt wells, and all plugged wells to be registered and to comply with applicable District Rules, including Well Construction Standards.

A summary of the number and type of applications processed and approved for authorizations, permits, and permit amendments including approved use types and commensurate permit volumes for production permits and amendments will be provided in the Annual Report.

2-1 PS 2-2, PS 2-3 (Existing wells)

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2-2 Ensure permitted wells and well systems are operated as intended by requiring reporting of periodic meter readings, making periodic inspections of wells, and reviewing pumpage compliance at regular intervals that are meaningful with respect to the existing aquifer conditions.

A. Inspect all new wells for compliance with the Rules, and Well Construction Standards, and provide a summary of the number and type of inspections or investigations in the Annual Report.

B. Provide a summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type in the Annual Report.

2-2 PS 2-3, PS 2-4, PS 3-1

2-3 Provide leadership and technical assistance to government entities, organizations, and individuals affected by groundwater-utilizing land use activities, including support of or opposition to legislative initiatives or projects that are inconsistent with this objective.

A. In even-numbered fiscal years, provide a summary of interim legislative activity and related District efforts in the Annual Report. In odd-numbered fiscal years, provide a legislative debrief to the Board on bills of interest to the District and provide a summary in the annual report.

B. Provide a summary of District activity related to other land use activities affecting groundwater in the Annual Report.

M-5 PS 1-6, PS 4-3

2-4 Ensure all firm-yield production permits are evaluated with consideration given to the Reasonable Use doctrine and demand-based permitting standards including verification of beneficial use that is commensurate with reasonable non-speculative demand.

A summary of the number and type of applications processed and approved for authorizations, permits, and permit amendments including approved use types and commensurate permit volumes for production permits and amendments will be provided in the Annual Report.

N/A

GOAL 3 - Addressing Conjunctive Surface Water Management Issues – 31TAC 356.52(a)(1)(D)/TWC §36.1071(a)(4) HCP Measures – Addressing Conjunctive Surface Water Management Issues

MP ID No.



2013 MP Standard*

159

3-1 Assess the physical and institutional availability of existing regional surface water and alternative groundwater supplies and the feasibility of those sources as viable supplemental or substitute supplies for District groundwater users.

Identify available alternative water resources and supplies that may facilitate source substitution and reduce demand on the Edwards Aquifer, while increasing regional water supplies, and evaluate feasibility by considering:

1. available/proposed infrastructure, 2. financial factors, 3. logistical/engineering factors, and 4. potential secondary impacts (development density/intensity

or recharge water quality). A summary of District activity related to this Objective will be provided in the Annual Report.

3-1 PS 5-1

3-2 Encourage and assist District permittees to diversify their water supplies by assessing the feasibility of alternative water supplies and fostering arrangements with currently available alternative water suppliers.

Identify available alternative water resources and supplies that may facilitate source substitution and reduce demand on the Edwards Aquifer, while increasing regional water supplies, and evaluate feasibility by considering:

1. available/proposed infrastructure, 2. financial factors, 3. logistical/engineering factors, and 4. potential secondary impacts (development density/intensity

or recharge water quality). A summary of District activity related to this Objective will be provided in the Annual Report.

3-2 PS 5-1

3-3 Demonstrate the importance of the relationship between surface water and groundwater, and the need for implementing prudent conjunctive use through educational programs with permittees and public outreach programs.

A. Provide summaries of associated outreach and education programs, events, workshops, and meetings in the monthly team activity reports in the publicly-available Board backup.

B. Summarize outreach activities and estimate reach in the Annual Report.

3-3 PS 4-4, PS 5-4

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3-4 Actively participate in the regional water planning process to provide input into policies, planning elements, and activities that affect the aquifers managed by the District.

Regularly attend regional water planning group meetings and annually report on meetings attended.

N/A

GOAL 4 - Addressing Natural Resource Issues which Impact the Use and Availability of Groundwater, and which are Impacted by the Use of Groundwater – 31TAC 356.52 (a)(1)(E)/TWC §36.1071(a)(5)

HCP Measures – Addressing Natural Resource Management Issues MP ID No.



2013 MP Standard*

4-1 Assess ambient conditions in District aquifers on a recurring basis by:

1. sampling and collecting groundwater data from selected wells and springs monthly;

2. conducting scientific investigations as indicated by new data and models to better determine groundwater availability for the District aquifers;

3. conducting studies as warranted to help increase understanding of the aquifers and, to the extent feasible, detect possible threats to water quality and evaluate their consequences.

A. Review water-level and water-quality data that are maintained by the District and/or TWDB, or other agencies, on a regular basis.

B. Improve existing analytical or numerical models or work with other organizations on analytical or numerical models that can be applied to the aquifers in the District.

C. A review of the data mentioned above will be assessed for significant changes and reported in the Annual Report.

4-1 PS 6-1, 4-2, 5-1, 5-2, 5-3, 6-2

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4-2 Evaluate site-specific hydrogeologic data from applicable production permits to assess potential impact of withdrawals to groundwater quantity and quality, public health and welfare, contribution to waste, and unreasonable well interference.

This involves evaluations of certain production permit applications for the potential to cause unreasonable impacts as defined by District rule. To evaluate the potential for unreasonable impacts, staff will:

1. Perform a technical evaluation of the application, aquifer test, and hydrogeological report;

2. Use best available science and analytical tools to estimate amount of drawdown from pumping and influence on other water resources; and

3. Recommend proposed permit conditions to the Board for avoiding unreasonable impacts if warranted.

A list of permit applications that are determined to have potential for unreasonable impacts will be provided in the Annual Report.

4-2 PS2-2, 2-3, 4-3, 6-2

4-3 Implement separate management zones and, as warranted, different management strategies to address more effectively the groundwater management needs for the various aquifers in the District.

A. Increase the understanding of District aquifers by assessing aquifer conditions, logging wells, and collecting water quality data. A summary of the number of water quality samples performed will be provided in the Annual Report.

B. A summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type will be provided in the Annual Report.

4-3 PS 2-1, PS 5-1

4-4 Actively participate in the joint planning processes for the relevant aquifers in the District to establish and refine Desired Future Conditions (DFCs) that protect the aquifers and the Covered Species of the District HCP.

Attend at least 75% of the GMA meetings and annually report on meetings attended, GMA decisions on DFCs, and other relevant GMA business.

4-4 PS 4-2

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4-5 Implement the measures of the District Habitat Conservation Plan (HCP) and Incidental Take Permit (ITP) from the U.S. Fish & Wildlife Service (USFWS) for the covered species and covered activity to support the biological goals and Objectives of the HCP.

Prior to ITP permit issuance, a progress report summarizing activities related to the USFWS review of the ITP application will be provided in the Annual Report. Upon ITP issuance, the HCP Annual Report documenting the District’s activities and compliance with ITP permit requirements will be incorporated into the Annual Report by reference.

N/A N/A

GOAL 5 - Addressing Drought Conditions – 31TAC 356.52 (a)(1)(F)/TWC §36.1071(a)(6) HCP Measures – Addressing Drought Conditions

MP ID No.



2013 MP Standard*

5-1 Adopt and keep updated a science-based drought trigger methodology, and frequently monitor drought stages on the basis of actual aquifer conditions, and declare drought conditions as determined by analyzing data from the District’s defined drought triggers and from existing and such other new drought-declaration factors, especially the prevailing DO concentration trends at the spring outlets, as warranted.

A. During periods of District-declared drought, prepare a drought chart at least monthly to report the stage of drought and the conditions that indicate that stage of drought. During periods of non-drought, prepare the drought charts at least once every three months.

B. A summary of the drought indicator conditions and any declared drought stages and duration will be provided in the Annual Report.

5-1 PS 3-2

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5-2 Implement a drought management program that step-wise curtails freshwater Edwards Aquifer use to at least 50% by volume of 2014 authorized aggregate monthly use during Extreme Drought, and that designs/uses other programs that provide an incentive for additional curtailments where possible. For all other aquifers, implement a drought management program that requires mandatory monthly pumpage curtailments during District-declared drought stages.

During District-declared drought, enforce compliance with drought management rules to achieve overall monthly pumpage curtailments within 10% of the aggregate curtailment goal of the prevailing drought stage. A monthly drought compliance report for all individual permittees will be provided to the Board during District-declared drought, and a summary will be included in the Annual Report.

5-2 PS 3-1, PS 4-2, PS 5-1

5-3 Inform and educate permittees and other well owners about the significance of declared drought stages and the severity of drought, and encourage practices and behaviors that reduce water use by a stage-appropriate amount.

A. During District-declared drought, publicize declared drought stages and associated demand reduction targets in monthly eNews bulletins and continuously on the District website.

B. A summary of drought and water conservation related newsletter articles, press releases, and drought updates sent to Press, Permittees, Well Owners and eNews subscribers will be provided in the Annual Report.

5-3 PS 3-1, PS 3-3, PS 4-4, PS 5-4

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5-4 Assist and, where feasible, incentivize individual freshwater Edwards Aquifer historic-production permittees in developing drought planning strategies to comply with drought rules, including:

1. pumping curtailments by drought stage to at least 50% of the 2014 authorized use during Extreme Drought,

2. “right-sizing” authorized use over the long term to reconcile actual water demands and permitted levels, and

3. as necessary and with appropriate conditions, the source substitution with alternative supplies.

A. Require an updated UCP/UDCP from Permittees within one year of each five-year Management Plan Adoption.

B. Provide a summary of any activity related to permit right sizing or source substitution with alternative supplies that may reduce demand on the freshwater Edwards Aquifer in the Annual Report.

5-4 PS 3-1, PS 5-1

5-5 Implement a Conservation Permit that is held by the District and accumulates and preserves withdrawals from the freshwater Edwards Aquifer that were previously authorized with historic-use status and that is retired or otherwise additionally curtailed during severe drought, for use as ecological flow at Barton Springs during Extreme Drought and thereby increase springflow for a given set of hydrologic conditions.

A summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type including the volume reserved in the freshwater Edwards Conservation Permit for ecological flows will be provided in the Annual Report.

5-5 IDective 3, PS 4-5

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GOAL 6 - Addressing Conservation and Rainwater Harvesting where Appropriate and Cost Effective – 31TAC 356.52 (a)(1)(G)/TWC §36.1071(a)(7)

HCP Measures - 6.2.1.6 Addressing Demand Reduction through Conservation

MP ID No.



2013 MP Standard*

6-1 Develop and maintain programs that inform, educate, and support District permittees in their efforts to educate their end-user customers about water conservation and its benefits, and about drought-period temporary demand reduction measures.

A. A summary of efforts to assist permittees in developing drought and conservation messaging strategies will be provided in Annual Report.

B. Publicize declared drought stages and associated demand reduction targets monthly in eNews bulletins and continuously on the District website.

C.

6-1 PS 3-3, PS 5-4

6-2 Encourage use of conservation-oriented rate structures by water utility permittees to discourage egregious water demand by individual end-users during declared drought.

On an annual basis, the District will provide an informational resource or reference document to all Public Water Supply permittees to serve as resources related to conservation best management strategies and conservation-oriented rate structures.

6-2 PS 3-1

6-3 Develop and maintain programs that educate and inform District groundwater users and constituents of all ages about water conservation practices and use of alternate water sources such as rainwater harvesting, gray water, and condensate reuse.

Summarize water conservation related newsletter articles, press releases, and events in the Annual Report. Summary will describe the preparation and dissemination of materials shared with District groundwater users and area residents that inform them about water conservation and alternate water sources.

6-3 PS 5-4

GOAL 7 - Addressing Recharge Enhancement where Appropriate and Cost Effective – 31TAC 356.52 (a)(1)(G)/TWC §36.1071(a)(7)

HCP Measures - 6.2.1.7 Addressing Supply through Structural Enhancement

MP ID No.



2013 MP Standard*

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7-1 Improve recharge to the freshwater Edwards Aquifer by conducting studies and, as feasible and allowed by law, physically altering (cleaning, enlarging, protecting, diverting surface water to) discrete recharge features that will lead to an increase in recharge and water in storage beyond what otherwise would exist naturally.

Maintaining the functionality of the Antioch system will be the principal method for enhancing recharge to the freshwater Edwards Aquifer. Additional activities may be excavating sinkholes and caves within the District. A summary of all recharge improvement activities will be provided in the Annual Report.

7-1 PS 5-2

7-2 Conduct technical investigations and, as feasible, assist water-supply providers in implementing engineered enhancements to regional supply strategies, including desalination, aquifer storage and recovery, and effluent reclamation and re-use, to increase the options for water-supply substitution and reduce dependence on the Aquifer.

Assess progress toward enhancing regional water supplies in the Annual Report.

7-2 PS 5-1, 5-3,

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GOAL 8 - Addressing the Desired Future Conditions of the Groundwater Resources – 31TAC (a)(1)(H)/TWC §36.1071(a)(8)

HCP Measures - 6.2.1.8 Quantitatively Addressing Established Desired Future Conditions MP ID No.



2013 MP Standard*

8-1 Freshwater Edwards Aquifer All-Conditions DFC: Adopt rules that restrict, to the greatest extent practicable, the total amount of groundwater authorized to be withdrawn annually from the Aquifer to an amount that will not substantially accelerate the onset of drought conditions in the Aquifer; this is established as a running seven-year average springflow at Barton Springs of no less than 49.7 cfs during average recharge conditions.

A. A summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type will be provided in the Annual Report.

B. Upon ITP issuance, the HCP Annual Report documenting the District’s activities and compliance with ITP permit requirements will be incorporated into the Annual Report by reference.

C. Upon ITP issuance, compile a summary of aquifer data including: 1) the frequency and duration of District-declared drought, 2) levels of the Aquifer as measured by springflow and indicator wells (including temporal and spatial variations), and 3) total annual and daily discharge from Barton Springs will be provided in the Annual Report.

8-1 PS 4-5

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8-2 Freshwater Edwards Aquifer Extreme Drought DFC: Adopt rules that restrict, to the greatest extent practicable and as legally possible, the total amount of groundwater withdrawn monthly from the Aquifer during Extreme Drought conditions in order to minimize take and avoid jeopardy of the Covered Species as a result of the Covered Activities, as established by the best science available. This is established as a limitation on actual withdrawals from the Aquifer to a total of no more than 5.2 cfs on an average annual (curtailed) basis during Extreme Drought, which will produce a minimum springflow of not less than 6.5 cfs during a recurrence of the drought of record (DOR).

A. A summary of the volume of aggregate groundwater withdrawals permitted and actually produced from permitted wells for each Management Zone and permit type will be provided in the Annual Report.

B. Upon ITP issuance, the HCP Annual Report documenting the District’s activities and compliance with ITP permit requirements will be incorporated into the Annual Report by reference.

C. Upon ITP issuance, compile a summary of aquifer data including: 1) the frequency and duration of District-declared drought, 2) levels of the Aquifer as measured by springflow and indicator wells (including temporal and spatial variations), and 3) total annual and daily discharge from Barton Springs will be provided in the Annual Report.

8-2 Objective 3, PS 4-2, PS 4-5

8-3 Implement appropriate rules and measures to ensure compliance with District-adopted DFCs for each relevant aquifer or aquifer subdivision in the District.

Develop and implement a cost-effective method for evaluating and demonstrating compliance with the DFCs of the relevant aquifers in the District, in collaboration with other GCDs in the GMAs. Prior to method implementation, provide a summary of activities related to method development in the Annual Report. Once developed, provide a summary of data for each District-adopted DFC for each relevant aquifer indicating aquifer conditions relative to the DFC and provide in the Annual Report.

N/A N/A

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HCP ID No.

HCP INDIRECT MEASURES HCP Mitigation Measures

Note: These Mitigation Measures are within the District’s general or specific authorities, but there are no associated performance standards

M-1 The District commits to supporting the operations of an existing refugium with facilities capable of maintaining backup populations of the Covered Species to preserve the capacity to re-establish the species in the event of the loss of population due to a catastrophic event such as an unexpected cessation of spring flow or a hazardous materials spill that decimates the species habitat. Such supplemental support would be provided through a commitment of in-kind, contracted support, and/or cash contributions that would contribute to:

a. Continuing the study of salamander physiology and/or behavior, and b. Conserving field and captive populations.

M-2 The District, in cooperation with the COA, commits to participating in conducting feasibility studies and, as warranted, pilot and

implementation projects to evaluate the potential for beneficial subsurface DO augmentation of flow in the immediate vicinity of the spring outlets and improved surface DO augmentation in the outlets (only) during Extreme Drought conditions. In-kind, contracted support, and/or cash contributions, phased during the term of the permit, may be authorized for feasibility studies and, if a project is feasible, for the pilot study and implementation of the augmentation project.

M-3 The District commits to extending the currently committed time period to operate the Antioch Recharge Enhancement Facility to continue after the 319(h) grant commitments (September 2014 or later), thereby improving recharge water quality and reducing nonpoint-source pollution at the outlets from runoff events during that time.

M-4 The District commits to establishing a new reserve fund for plugging abandoned wells to eliminate high-risk abandoned wells as potential conduits for contaminants from the surface or adjacent formations into the aquifer, with priority given to problematic wells close to the Barton Springs outlets and/or associated with water chemistry concerns under severe drought conditions. This reserve fund, which like others under state law has restrictions on its funding and use, would be established within the first year after issuance of the ITP by closing the existing Drought Reserve Account, whose stipulated purpose has been legal defense for drought management, and then by utilizing its current balance to initially fund a new Aquifer Protection Reserve Account. The new account would exist solely to fund plugging of abandoned wells and would be replenished after the first year with any collected enforcement penalties, any drought management fees imposed on larger nonexempt permittees that do not meet their drought curtailments, and an annual budgeted supplement at the discretion of the Board.

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M-5 For the term of the ITP, the District commits to provide leadership and technical assistance to other government entities, organizations, and individuals when prospective land-use and groundwater management activities in those entities’ purview will, in the District’s assessment, significantly affect the quantity or quality of groundwater in the Aquifer. The District will respond actively and appropriately to legislative initiatives or projects that affect Aquifer characteristics, provided such actions are consistent with established District rules, ongoing initiatives, or existing agreements.

* The proposed HCP Direct Measures were developed by the District at the same time as, and incorporated within, the 2013 Management Plan, so the Draft HCP referenced the 2013 Management Plan’s objectives and identified their performance standards specified in this column. Shortly before the Final HCP was completed, the Management Plan was revised on its normal five-year cycle, and while the HCP Measures did not substantively change, the corresponding Management Plan objectives and their associated performance standards were updated and expanded, as shown in this table.

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6.3 Monitoring Activities

All of the District operations are based on the philosophy that, “You can’t manage what you

don’t measure.” The HCP program will be no different, and the District will routinely and

regularly monitor a suite of parameters that delineate its progress and outcomes, and the

continuing implementation of the adaptive management process (Section 6.4, District HCP

Adaptive Management Process) to improve performance. These monitoring activities, many of

which are already being done, address Aquifer characteristics, Covered Species status, and

overall conservation program management and performance. The monitoring program to be

used by the District is described in detail in the following subsections. In addition, the

monitoring data will be reported to and assessed annually by the Board and by the HCP

Management Advisory Committee (MAC) as part of the HCP compliance monitoring and

reporting initiatives, as described below. Monitoring data collected, data analysis conducted, and

groundwater management activities undertaken in the course of each year of the HCP will be

summarized in an annual report to the Service, as described in more detail in Section 6.5.1.1,

Administration and Reporting.

6.3.1 Monitoring Groundwater Management Actions

Aquifer management will focus on an array of conservation measures directly or indirectly

affecting the withdrawal of water from wells in the Aquifer to maintain springflow in Barton

Springs, as outlined in Section 6.2.1, Direct HCP Measures.

A validation monitoring program will be developed and implemented to measure future success

of Aquifer-management activities, and to modify management actions on the basis of new

information. This program will be conducted in collaboration with the COA under an ILA for

each entity’s HCP monitoring reports. The District will seek to finalize the ILA with the COA as

soon as possible after the issuance of the ITP. The validation monitoring program will be

promulgated and initially implemented within the first year following execution of the ILA. The

following data and information will be compiled by the District for this HCP each year, reviewed

annually by the Board and the HCP MAC, and reported annually to the Service:

• Survey data on the Covered Species, now collected quarterly by the COA; water quality and

habitat data collected by the District, COA, USGS, and/or other entities; and trends in water

quality and habitat data, all of which will be used to consider the need to re-evaluate

biological risk during low-flow conditions;

• Results of any numerical or analytical modeling of the Aquifer and salamander population

dynamics on which the HCP is based that are reported each year, to assess the current worth

and continuing validity of such tools and concepts; and

• Available data on the total annual discharge of Barton Springs, its temporal and spatial

variations, and the aggregate withdrawals from wells in the Aquifer, to inform periodic

water-balance (inflows to and outflows from the Aquifer) modeling.

In the first year of the ITP term, the District will collaborate with the COA to formulate a

methodology for monitoring and evaluating take associated with the District’s Covered

Activities. This methodology will use existing springflow gaging, water chemistry monitoring,

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and salamander censuses, supplemented by new data collection and analyses by the COA as

defined in the MOU/ILA between the COA and the District. Following review by the MAC and

subsequent review and approval by the Board, the monitoring methodology will be submitted to

the U.S. Fish & Wildlife Service (Service) for its concurrence with the first annual report after

the first full year of operating under the ITP. The activities required by the collaborative take

monitoring methodology will be an element in the prospective ILA between the COA and the

District.

6.3.2 Monitoring HCP Effectiveness

The District determines actual groundwater withdrawals through required monthly water-use

reports from all nonexempt users. The Board reviews reported metered data on a periodic basis

during declared drought, and confirms/clarifies withdrawal trends in the District, both overall

and by permittee. Setting of the meters and their calibration are required to be in compliance

with standards and rules of the District. The results of comparisons of metered groundwater

withdrawals relative to then-authorized amounts, including both aggregate and individual

permittee performance, are the fundamental tool used to monitor effectiveness of the District

HCP and MP with respect to managing withdrawals from the Aquifer.

To monitor overall effectiveness of the District HCP measures, a process will be developed to

collect relevant data and define trends for a set of HCP performance metrics, including:

• Frequency or necessity of Stage II Alarm-, Stage III Critical-, and Stage IV Exceptional-

Drought Measures;

• Levels of the Aquifer as indicated by springflow and water levels in designated

(indicator) wells;

• Daily mean discharge from Barton Springs;

• Through coordination with COA staff, reporting of:

o current and historical biological data to evaluate responses to groundwater

management actions during any low-flow conditions;

o availability of suitable habitat during various low-flow conditions,

o relative salamander abundance and population characteristics based on observations

during low-flow and other conditions,

o water-chemistry characteristics related to flow through the spring orifices during

normal and low-flow conditions, and

• Educational outreach program summaries, including quantity, quality, and timeliness of

information disseminated to the general public and stakeholders about water use, demand

management, and aquifer conditions.

These performance metrics will be compiled and analyzed on a continuing basis and presented in

a comprehensive report to the HCP MAC and to the Service on or before the third-year

anniversary of ITP issuance, and every five years thereafter, for the duration of the ITP. This

more analytical, comprehensive report is in addition to the more data-driven annual reporting to

the Service, and it would incorporate and constitute that annual report for the year of its issuance.

The District will, in coordination with the COA and under the auspices of the ILA that both

entities intend to inform their respective HCPs, obtain and report biological survey data and

analyses being evaluated on a continuing basis by the COA. The District believes the COA's

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biological data collection activities under its Barton Springs Pool HCP are sufficient for the

purposes and needs of the proposed direct measures of the District HCP, with no benefit in

duplicative efforts nor need to augment the frequency or extent of current COA data collection.

Changes in the effectiveness of the HCP direct measures and/or new requirements arising from

implementing specific mitigation measures such as DO augmentation processes may create the

need for collection of additional information of various types, including water chemistry and

biological data collection, to gauge effectiveness. As specific data needs and gaps are identified

that may require a focused research effort (corresponding with adaptive management measures

specified in Section 6.2, Minimization and Mitigation Measures, or in the Adaptive Management

Plan [AMP]), the District will consult with the Service and the COA and commit resources for

such research, to the extent that additional funds and in-kind labor are available (see Section 8,

District HCP Funding Assurances, for details on funding).

6.3.3 Monitoring HCP Implementation

The District will ensure that all HCP management objectives are realized as indicated by the

performance metrics, through a commitment to managing the execution of the MP to achieve

those outcomes. Any indicated issues and exceptions will be reported to the Board at least

monthly, and then, as warranted, to the Service for further consultation. These results will also

be documented using the annual reporting procedure outlined in Section 6.5.1.1, Administration

and Reporting.

6.4 District HCP Adaptive Management Process

The District reasonably believes that the initial HCP conservation measures to be funded by the

District for its HCP will be effective in conserving habitats and the Covered Species for the term

of the ITP. However, monitoring the implementation of these measures will provide continuing

feedback on the efficacy of those measures, The District also is committing to pursuing a

continuing, focused research program that may produce data and new information that can be

used to identify and evaluate improvements and other potential management options; the specific

research areas for pursuit under the District HCP are described below in Section 6.4.1, Research

Supporting the AMP. In addition, over time Changed and Unforeseen Circumstances (Section 7)

may affect the status of habitats and the condition of the species within the Barton Springs

ecosystems; and the uncertainties identified in Section 7.2.1, Considering Specific Uncertainties,

may be resolved or clarified. All of these initiatives, both individually and in aggregate, will

inform the District HCP’s Adaptive Management Program (AMP).

6.4.1 Research Supporting the AMP

The District proposes to conduct research in several specific areas to address known

uncertainties and thereby inform the AMP. Research focused on these areas is characterized in

this subsection.

• During the term of the ITP, the District commits to collaborating with universities, the COA,

and other qualified parties on projects to better inform and determine the level of risk

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associated with Aquifer level- and springflow-related changes in water chemistry affecting

the viability and recovery of the Covered Species’ population, by supporting:

1. Surveys of the temporal and spatial DO variability of the Aquifer and the surface

environments around the Barton Springs complex and at more remote habitat locations,

2. Investigations of salamander habitat in the Aquifer in the vicinity of existing active

monitor wells and future monitor wells close to Barton Springs and at more remote

habitat locations.

3. Continued support of laboratory stressor-response studies of salamander species, and/or

4. Efforts to restore the spring-run habitat and explore other possibilities to improve re-

aeration at the spring outlets.

It is envisioned that this research will begin in Year 1 and continue each year through the ITP

term. Much of the level of effort for this measure will be expended in the first five years, as

it will form an important basis for evaluating the feasibility and guiding the implementation

of subsequent mitigation projects. Additionally, the District and the City of Austin will

negotiate the MOU/ILA in the first year to guide the implementation of many of the indirect

measures throughout the ITP term. The District currently plans to commit cash contributions,

in-kind labor, and contracted support in an aggregate amount of $380,000 to this research

area over the ITP term.

During the term of the ITP, the District commits to collaborating with the USGS, the TWDB,

universities, the COA, Edwards Aquifer Authority, and other qualified parties to: 1. Develop a refined conceptual model to improve the numerical models for the District

aquifers, and

2. Improve hydrogeologic characterization of aquifer function during extreme low flows,

including assessments of new potential recharge sources from urban recharge and

bypasses from the San Antonio segment, and their changes over the term of the ITP.

Some of the tasks currently envisioned to be a part of the research program in this area are: 1)

monitor well program with installation of a standard and multiport monitor well close to

Barton Springs; 2) dye trace program for injecting dye in the monitor wells and measuring

discharge of dye at the springs; 3) measurements of DO distribution in the Aquifer; and 4)

testing of DO augmentation in the Aquifer. This research will begin in Year 1 and continue

at a roughly constant level over the ITP term. The District currently plans to commit cash

contributions, in-kind labor, and contracted support in an aggregate amount of $300,000 to

this measure over the ITP term.

6.4.2 AMP Process to Be Used in the District HCP

Historically, the District has used an “incremental/rational planning” approach to adaptive

management as an accepted resource management practice and as an integral part of rulemaking

as its drought management planning has evolved (Section 4.1.2, Historical Perspective of

Covered Activities). For the HCP, the District has evaluated and will also employ, where

feasible, the specific AMP protocols implemented by the U.S. Department of the Interior (DOI)

in its Adaptive Management Implementation Policy (DOI, 2008) and stipulated for use in HCPs

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by the Service, an agency of the DOI. Passive adaptive management in a general sense has been

a primary means by which the District evaluates and incorporates alternative management

actions. This will continue under the HCP as the proposed measures are implemented, as

monitoring data are collected, and as uncertainties in the natural systems are resolved. Over

time, new management activities will be added under the direct measures for avoidance,

minimization, and mitigation as they prove prudent, feasible, and warranted, using the

DOI/Service AMP protocol if and when it is appropriate and the District’s own

incremental/rational planning approach when it is not.

The DOI/Service AMP protocol is an active, structured process and a defined method for

addressing uncertainty in natural systems when:

• One or more issues can be articulated as outcomes of management options,

• A relatively frequently recurring decision must be made (which allows for regular and

controlled testing and therefore optimization of results),

• Various management approaches or strategies can be applied by an agency to the system to

affect observable results on a planned, iterative basis,

• Uncertainty can be expressed in terms of testable hypotheses or models of management

options, and

• Monitoring can be designed and implemented to reduce uncertainty and deliver timely

conclusions that can affirm or be used to adjust resource management outcomes for the next

iteration of testing.

Section 7.2.1, Considering Specific Uncertainties, identifies a number of uncertainties that may

affect the HCP during the term of the ITP. The main management issues for the District HCP

arising from these uncertainties are:

• What are the physical and hydrochemical responses of the Aquifer system during Extreme

Drought conditions that are equivalent to a recurrence of the DOR, as those conditions have

not occurred since the Covered Species were first identified?

• Does the existing DFC of the Aquifer during Extreme Drought—that is, monthly mean

springflow no less than 6.5 cfs (0.18 m3/s) — along with the proposed mitigation measures

actually result in, as intended, water chemistry that allows the populations of the Covered

Species to survive and to recover?

• Does the ability of the Covered Species to migrate into the subsurface environment between

and around spring outlets provide a safe harbor when the surface environment is critically

deficient in one or more of their life requirements?

• Do re-established spring runs provide sufficient re-aeration at the spring outlets to provide a

safe harbor for one or both of the Covered Species during Extreme Drought conditions?

• Does provision of alternative water supplies to existing users of the Aquifer translate

confidently into actual reductions in withdrawals from the Aquifer during drought periods

and into increased springflow?

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These issues constitute the focal points and potential objectives for this HCP’s adaptive

approaches.

For the direct HCP measures (Section 6.2.1, Direct HCP Measures) that form the existing

program in the approved District Management Plan, the District will continue to evaluate its

proposed HCP conservation measures using its currently implemented incremental/rational

planning approach to AMP to help resolve the issues described above. For example, if pertinent

new statutory authority is provided by the Texas Legislature to GCDs such that the District

could differentiate levels of curtailment during Extreme Drought by groundwater use type

(currently not legally possible), the District would consider and then could adjust its drought

curtailment program to reduce withdrawals by certain types of permittees even more and thereby

further minimize take of the Covered Species.

However, if monitoring data and outcomes of the proposed HCP implementation, including

mitigation measures and/or research results, suggest modification of the current measures or

additional measures are warranted, the District will consider utilizing the DOI AMP in lieu of its

own incremental/rational planning approach to AMP to evaluate new indirect measures and

monitor controls on their effectiveness. Such an assessment may be most amenable for certain

mitigation projects requiring isolation and testing of variables under controlled conditions. For

example, the planning, design, and implementation of a phased DO augmentation testing

program may be able to be conducted as a DOI AMP, although there will be additional trade-offs

on costs, risks, and acceptability that would have to be assessed. (Such an AMP initiative would

need to be conducted under the auspices of and with the various approvals by the Service under

both the COA’s and the District’s ITPs/HCPs and with various agreements and responsibilities

specified in the prospective ILA between the COA and the District.)

6.5 Implementation Roles of Plan Participants

The District is applying for a 20-year ITP to allow incidental take of Covered Species in the

Barton Springs ecosystem. Responsibilities of the participant and cooperating entities are

outlined below. The ITP generally will specify responsibilities of the permit holder,

conservation and mitigation measures to be implemented, monitoring and research procedures,

and any other permit conditions that may be required, and the District will ensure they are

addressed during HCP implementation.

6.5.1 Barton Springs/Edwards Aquifer Conservation District

The District, or BSEACD, is the applicant for the ITP and is the only Participant, as the term is

defined by the Service, in the District HCP. The District will be the ITP holder. The ITP will

cover the District, as the groundwater management entity, and all groundwater producers in the

District’s jurisdiction that hold production permits from the District, as the authorized users of

groundwater being managed by the District.

As the District issues and renews groundwater production permits, the permittees’ water-use fees

and other fees paid by the COA that are associated with use by the permittees will generate

funding for the HCP. Typically and generally, this funding will support implementation of the

HCP conservation program and the administration and reporting associated with the HCP by

offsetting the direct and indirect cost of internal labor and other direct costs. The bulk of the

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funding commitment discussed in Section 8, District HCP Funding Assurances, will be used in

this way. Beyond the internal support needs of the HCP, the District will distribute part of this

revenue to other entities, if and as authorized by bilateral contractual agreements; or to pay for

in-kind services of the District and for external goods and services provided by other entities.

The District will be responsible for implementing drought-stage management as well as

comprehensive management of the aquifer, using its rules and statutory authorities, and for

monitoring compliance and effectiveness.

The District will report no less frequently than annually to the Service on the status of Aquifer

withdrawals, drought-stage management, results of monitoring programs, efficacy and issues

associated with minimization and mitigation measures, and adaptive management needs and

opportunities.

Details on each of these processes are presented in the following subsections.

6.5.1.1 Administration and Reporting

The District will provide to the Service an annual report on the progress of and plans for

implementing the District HCP during the preceding fiscal year, to be published no later than the

end of February each year, as to be specified in the ITP. The first annual report will be provided

to the Service no later than the first February 28th following completion of the first 12-month

period of operating under the ITP. More specifically, this report will summarize information on

the management and monitoring of the Aquifer including:

• Reported groundwater withdrawals from permitted wells;

• Reference well levels;

• Springflow at Barton Springs;

• Total Aquifer discharge, measured for permitted wells, estimated for exempt wells,

gaged/measured for Barton Springs; and estimated for Cold & Deep Eddy Springs;

• Drought-stage management reductions;

• Estimated actual take, if any, for the annual reporting period, and total cumulative take for

the ITP term;

• Minimization measures and actions taken during the prior year;

• Mitigation actions taken during the prior year and updates on ongoing mitigation actions

including the progress of DO augmentation investigations, as well as recharge facility

management;

• Adaptive management activities undertaken during the year or indicated as prudent by

outcomes of the conservation program;

• Expenditures by the District on implementation activities; and

• Proposed HCP-related activities for the next reporting period.

In addition, the report will summarize any groundwater management actions undertaken by the

District and any species-specific research reports compiled or completed by investigators in the

reporting year that relate to the biological objectives identified for the Covered Species or

improvements in the assessment of and appropriate responses to actual take. This annual report

may also contain other, non-HCP information and may also be used to report the progress and

plans of the District as a GCD to the Texas Commission on Environmental Quality (TCEQ), as

required by District bylaws.

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This annual report will be submitted simultaneously to the Service and to the HCP MAC,

described in the subsection immediately following, for their respective review and comment by

February 28th each year. This date is specified so as to allow data and analyses conducted by the

COA under its HCP to be vetted and supplied to the District for this HCP.

6.5.1.2 District HCP Management Advisory Committee

The District has established an HCP MAC to advise and assist the Board in the coordination of

conservation activities affecting Covered Species at Barton Springs, and in monitoring and

helping the Board improve the implementation of the District HCP for the District. This MAC is

an additional measure to ensure continued improvement of the HCP and compliance with the ITP

as well as to ensure the Board is aware of any stakeholder concerns regarding the execution of

the HCP and revisions to the HCP. The primary purpose of the MAC is to review and comment

to the District’s Board of Directors on the District’s HCP annual reports or on selected aspects of

those reports, in a manner of the MAC’s choosing, in its continuing improvement role. In this

role, the MAC is intended to be largely self-directed. At the Board’s discretion, the MAC may

also be requested to:

• Provide a forum for exchange of information relative to Covered Species,

• Provide ad hoc advice on Covered Species management activities,

• Advise the District on priorities for conservation actions, as warranted, and

• Provide input and recommendations, as warranted, on the development and implementation

of actions through the adaptive management program.

The MAC was appointed by the District Board in early 2013 and includes independent, volunteer

representatives with biological or natural-resource management responsibilities from designated

interest groups. MAC composition focused on perspectives useful to the active management of

the Aquifer and the habitat of Covered Species at Barton Springs. The interest groups that

compose the MAC are:

Texas Parks and Wildlife Department (TPWD)

City of Austin Watershed Protection Department (COA WPD)

Environmental community

Technical/ecological research expertise

Salamander biologist/expert

Public water-supply permittee

Large private-sector permittee

Aquifer-using landowner

Private property conservation interests

River authority

County government

Interested private citizen/public at-large (2)

District technical staff

The Service was also requested to provide a non-voting representative to be liaison between the

District, the Service, and the MAC.

This MAC is a standing advisory group to the Board for the HCP. The individuals serving as

MAC members are reasonably expected to change from time to time over the 20-year term of the

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ITP. However, provided replacement members are appointed by the District Board from the

same interest group, and such changes are proposed to be considered administrative.

The MAC will convene in some manner appropriate to the purpose of each meeting and no less

frequently than annually, and at such other times as they decide or as requested by the Board.

The MAC at its discretion may form subcommittees to address specific issues or topical areas

pertinent to the HCP and the MAC’s charge. It will receive and review the District’s annual

progress report and associated other documentation pertaining to the ITP. In a forum of its

discretion each year, it will evaluate HCP progress and identify any concerns that a consensus of

the MAC finds important to convey; and at its discretion, report its findings in a presentation

directly to the District Board each year.

In addition, every five years the MAC will review the District-prepared report on the

performance of the HCP measures, as described in Section 6.3, Monitoring Activities, and make

recommendations for adjustments or improvements, as warranted, in a letter report to the

District’s Board.

6.5.1.3 Adaptive Management Process

The District may implement an adaptive management process as appropriate to address:

• Guiding long-term aquifer-management monitoring and research planning,

• Further defining critical attributes and linkages within and between physical components of

the spring ecosystem,

• Promoting improved understanding of uncertainties and other key factors that drive changes

in the spring ecosystem,

• Making qualitative and quantitative assessments of resource changes resulting from flow

variation and impacts to the Covered Species, and

• Providing information to stakeholders regarding the potential impacts and benefits of flow

variation in the Barton Springs ecosystem.

Certain direct and indirect measures, especially mitigation measures, as presented in Table 6-1,

and the actions taken in response to Changed and Unforeseen Circumstances (Section 7), may

identify needs for additional specific research and a specific adaptive management response.

These needs will be characterized and future action recommended, if feasible, in the Annual

Report. As appropriate and feasible, a future AMP project will conform to the DOI/Service

technical guidance document, as discussed in Section 6.4, District Adaptive Management

Process.

6.5.1.4 District Enforcement Program

The District has established an aggressive enforcement program under District Rule 3-8,

Enforcement (Appendix K provides the entire District Board-approved Enforcement Plan). The

District enforces all of its Rules, whether for permit violations (for example, overpumpage),

well-construction violations, wasteful water use, or failure to make timely use reports and fee

payments. Enforcement measures are, in typical order of their use: warning letters, assessment of

fines and penalties through agreed-upon enforcement orders, show-cause hearings, “red-tagging”

of wells that limit or prohibit withdrawals from permitted wells, temporary suspension of

permits, revocation of permits, and finally litigation in District court (which is rarely needed).

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Under District policy, enforcement priorities in any one drought stage focus first on the most

egregious non-compliant users, those with the largest amounts of permitted pumpage and/or

those with the largest percentage of monthly overpumpage.

Of particular note with respect to the District HCP are the enforcement measures and penalties

that have been established during declared droughts. Each day that a violation occurs is a

separate violation, and the penalties are cumulative. Every District permit contains both a User

Conservation Plan (UCP) and a User Drought Contingency Plan (UDCP) as an agreed part of the

permit, specifying both voluntary and mandatory actions that the permittee and end users, as

warranted, will take under various drought stages. The UDCPs include drought-time curtailment

charts that specify the allowed pumpage each month during various drought stages and

emergency response periods of various durations. Penalties related to pumpage violations during

Stage III Critical- and Stage IV Exceptional- Drought carry twice the dollar fines as those during

Stage II Alarm Drought. These penalties have been determined to have considerable deterrent

value and success in attaining compliance with District pumpage regulations.

The daily penalties for violations related to failure to reduce pumpage during District-declared

drought are shown in Table 6-2 below. Changes to the penalty structure and amounts that do not

adversely affect compliance and therefore take would be a proposed administrative change under

the HCP and not require an HCP or ITP amendment.

Table 6-2a: Daily penalties for violations of District drought rules during Stage II-Alarm Drought,

Rule 3-7.7.B(1).

Overpumpage Level

Level A Level B Level C

Tier 1 $50–$100 $100–$200 $200–$400

Tier 2 $200–$400 $400–$800 $800–$1,600

Tier 3 $800–$1,600 $1,600–$3,200 $3,200–$5,000

Table 6-2b: Daily penalties for violations of District drought rules during Stage III-Critical and

Stage IV-Exceptional Drought, Rule 3-7.7.B(2).

Overpumpage Levels

Level A Level B Level C

Tier 1 $100–$200 $200–$400 $400–$800

Tier 2 $400–$800 $800–$1,600 $1,600–$3,200

Tier 3 $1,600–$3,200 $3,200–$6,400 $6,400–$10,000

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Table 6-2c: Definition of tiers of permitted pumpage and levels of overpumpage during all drought

stages.

Permitted Pumpage, in gallons/year: % Pumpage Over Monthly Target:

Tier 1: < 12,000,000 (45 million liters/year) Level A: < 25%

Tier 2: ≥ 12,000,000 and < 120,000,000 Level B: > 25% and < 100%

Tier 3: ≥ 120,000,000 (454 million liters/year) Level C: > 100%

6.5.2 Cooperating Federal and State Agencies

6.5.2.1 U.S. Fish and Wildlife Service

The Service is the federal agency responsible for issuing the ITP and monitoring compliance

with the ITP conditions. The Service, as the regulatory agency for the District ITP, will review

and comment on the Annual Report and other HCP monitoring reports provided by the District.

6.5.2.2 Texas Parks and Wildlife Department

The Covered Species are also species listed by the TPWD as Species of Greatest Conservation

Need (TPWD, 2012), and therefore the TPWD is a supporting governmental entity of this HCP.

Involvement by the TPWD as well as other State governmental agencies and political

subdivisions in the development of HCPs is guided by provisions of Subchapter B, § 83.011

through §83.020 of the Texas Statutes, Parks and Wildlife Code. These subsections lay out

definitions of HCP; regional HCPs; land development standards; and plan participants, structure

and function of advisory committees; and provide guidance for acquiring habitat preserves.

TPWD is also providing a member of the proposed MAC to assist the District in the

implementation of the District HCP. Other TPWD activitiesincluding biological consultation,

coordination, or participation in future adaptive management strategiesremain unspecified and

will be consistent with TPWD authorities and needs during the implementation of the HCP.

6.5.3 City of Austin and Barton Springs Pool HCP

The COA is not an applicant in the District HCP. However, the COA, which is traditionally a

collaborative partner with the District in many of its programs, is currently providing a

substantial portion of the total funding for the District, including in part the conservation

measures of the District HCP. In addition, the COA has a complementary HCP for operation and

maintenance of Barton Springs Pool (City of Austin, 2013.) The District intends to take

advantage of the opportunities that likely exist for beneficial interaction between the two related

HCPs. Under the District HCP, the District and the COA propose to collaborate through an ILA

and/or an MOU in the following areas, and as others arise from the District’s adaptive

management process and are agreed by the parties:

• Provision of monitoring data (on both routine and exception bases) and their evaluation

reports, in preliminary and final formats, to the District so that mutual interests on the

viability of the Covered Species and on aquifer/spring dynamics are being met;

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• Collaboration and participation with the District in long-range planning, to provide COA

water supplies and possibly other alternative sources to new and existing communities and

businesses in the District HCP Planning Area in lieu of Aquifer water supply;

• Collaboration, participation, and procedures, as appropriate, in a variety of research

investigations, mitigation measures, and adaptive management measures, as specified in

Section.6.2.2, Other HCP Measures and Strategies, Including Mitigation;

• Communications, collaboration, and provisions concerning both required and prohibited

activities during severe drought in the immediate vicinity of the spring outlets and Barton

Springs Pool; and

• Continuing collaboration with the COA in dye tracing, springflow measurement, and the

adjustment and validation of low-springflow rating curves (a rating curve here refers to the

relation between springflow and the water level in a nearby Aquifer well).

The ILA provision that a knowledgeable COA representative will be on the MAC will be

invaluable in conveying the results and conclusions of the COA's complementary investigations

and activities to other members of the MAC.

6.5.4 Other Entities

Other governmental entities, political subdivisions, universities, or private research groups may

be involved cooperatively in conducting studies or other actions identified or included as District

HCP measures. If they become an essential condition in maintaining ITP compliance, specific

responsibilities of the parties would be identified in District HCP contracts or implementation

agreements with the District. The current statutory and/or management responsibilities of certain

entities could either directly or indirectly affect HCP implementation:

• U.S. Geological Survey—This agency administers programs to monitor Aquifer recharge,

springflow, water levels, and water quality. The USGS currently operates monitoring wells

and records and transmits to appropriate offices water level data at both sites that the District

uses in its drought-trigger methodology for assessing drought stages.

• Texas Commission on Environmental Quality—This agency manages and protects water

quality through regulation of point- and nonpoint source water pollution in the Edwards

Aquifer and the contributing surface watershed. TCEQ also serves as the administrative

regulatory authority for all GCDs in the state, including the District.

• Texas Water Development Board—This agency will review and approve the District’s MP

and provide additional support to the District on compliance with state laws pertaining to

groundwater management, especially those related to specifying the Modeled Available

Groundwater associated with DFCs.

• Other Groundwater Conservation Districts—The five other GCDs in GMA 10 are statutorily

charged with establishing and reviewing the DFCs for the Aquifer at least every five years.

A two-thirds super-majority is required to amend and approve (and re-adopt) the DFCs set by

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the GMA. In addition, GCDs in GMA 9, especially the Hays Trinity GCD and Blanco

Pedernales GCD, authorize withdrawals from the Trinity Aquifer in the Contributing Zone of

the Barton Springs segment of the Edwards Aquifer, which may affect the quantity and

quality of contributions of base flow to the up-gradient creeks that recharge the Aquifer.

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7.0 Changed and Unforeseen Circumstances

Regulations implementing Section 10 of the Endangered Species Act (Act) (50 CFR

17.22(b)(2)(iii)) require that a Habitat Conservation Plan (HCP) specify the procedures to be

used for dealing with Changed and Unforeseen Circumstances that may arise during HCP

implementation. In addition, the HCP Assurances (“No Surprises”) Rule (50 CFR 17.2,

17.22(b)(5) and (6); 63 FR 8859) defines “Unforeseen Circumstances” and “Changed

Circumstances,” and describes the obligations of the permittees and the U.S. Fish & Wildlife

Service (Service) under such circumstances.

7.1 Responding to Changed Circumstances and Unforeseen

Circumstances

The District has made a concerted effort to anticipate the minimization and mitigation measures

(conservation measures) and monitoring that are necessary to conserve the Covered Species and

preserve the habitats that support the species and that are within its statutory authorities. To that

end, the District has relied upon the best scientific and experience-based information available in

preparing this HCP. The District also sponsored and contracted for original research and for

relevant new data to be collected as a part of the District HCP development process to provide

new information, to complement existing knowledge, and to manage groundwater withdrawals

and springflow for the benefit of the Covered Species. In addition, the flexible provisions

regarding the expenditure of funds authorized by the District Board for specific mitigation

measures, including the indirect measures described in Section 6.2.2, Other HCP Measures and

Strategies, and specifically the adaptive management planning processes in Section 6.4, District

HCP Adaptive Management Process, are designed to address future needs and emergency

situations. Thus, the District HCP intends to minimize the potential for adverse Changed or

Unforeseen Circumstances on the Covered Species and its habitat.

However, these provisions notwithstanding, Changed or Unforeseen Circumstances may occur

during the course of a long-term permit program like the ITP. So provisions for addressing such

conditions are part of each HCP. In this context, only those circumstances that the Covered

Activities may affect or may be affected by are relevant to the District HCP.

The District HCP’s AMP is one mechanism that the District will use to anticipate optional

responses and evaluate outcomes to certain Changed Circumstances and Unforeseen

Circumstances. Additional information on how the District will respond to these circumstances

follows.

7.1.1 Resolving Adverse Changes

A principal aspect of the HCP is a commitment by the District that (a) should certain Changed or

Unforeseen Circumstances result in or threaten a substantial adverse change in the population of

the Covered Species or the overall quality of any habitat of the species, and ( b) should it be

determined that the Covered Activities contribute to either the cause or the resolution of the

adverse change, as determined pursuant to the procedure outlined herein, the District and the

Service shall cooperate to resolve the adverse impacts in accordance with the definitions and

guidance provided by the Services’ HCP Assurances (“No Surprises”) Rule:

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• For Changed Circumstances—If additional conservation and mitigation measures for the

Covered Activities are deemed necessary to respond to changes in circumstances provided

for in the District HCP, the District as the ITP permittee will be expected to implement the

responsive measures specified in the HCP, but only those measures and no others; and

• For Unforeseen Circumstances—The Service statutorily may not require the commitment

of additional land or water resources or financial compensation—including additional

restrictions on the use of land, water, or other natural resources—even upon a finding of

Unforeseen Circumstances, unless the permittee consents. Upon a finding of Unforeseen

Circumstances, the Service may have only limited ability to require additional measures or

modifications within the conserved habitat areas that are inconsistent with the District’s

approved Management Plan (MP) that authorizes its groundwater management program and

the District HCP. Additional required conservation and mitigation measures will not involve

the commitment of additional land, water, or financial compensation or additional restrictions

on the use of land, water, or other natural resources.

Consultation between the Service and the District also may indicate that the adverse changes

may be most appropriately addressed through an amendment of the ITP and HCP.

7.1.2 Method for Developing Criteria for Changed Versus

Unforeseen Circumstances

The District has determined that changes in several specific circumstances are reasonably

foreseeable and therefore should not be considered unlikely to occur during the course of the

HCP and the term of the ITP. The District has determined which of these are related to Covered

Activities of the District HCP and are therefore actual Changed Circumstances under the Act.

These circumstances are discussed in Section 7.2.2, Considering and Responding to Changed

Circumstances, which identifies the specific responses included as part of this HCP and commits

the District to take those actions. Not reasonably foreseeable and Unforeseen Circumstances

(Section 7.3, Unforeseen Circumstances) could also affect the District HCP, as provided for

under the Service’s HCP rules and guidelines. In addition, several factors that influence the

ecosystem are either not known or only poorly known, as indicated in Section 7.2.1, Considering

Specific Uncertainties. The likelihood of those factors affecting HCP conservation measures is

uncertain. They could result in either Changed or Unforeseen Circumstances. The District will

consult with the Service and seek a determination by the Service whether a particular event or

change in a relevant circumstance or factor constitutes a Changed or Unforeseen Circumstance

under the District HCP, generally on the basis of the likelihood of the change or event reasonably

being anticipated to occur during an average 20-year period (the proposed term of the District

HCP) and reasonably being related to the Covered Activities. The respective responsibilities of

the District and the Service in determining Unforeseen (and therefore not “Changed”)

Circumstances are discussed in Section 7.3.1, Responding to Unforeseen Circumstances.

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7.2 Changed Circumstances and Uncertainties

The Service defines the term “Changed Circumstances” to mean “changes in circumstances

affecting a species or geographic area covered by a conservation plan…that can reasonably be

anticipated by plan…developers and the Service, and that can be planned for” (40 CFR §17.3).

Examples provided include listing of new species in the plan area (Section 7.2.2.1, Listing of

New Species Not Covered by the HCP) or some extreme event in areas prone to such events,

most notably drought severity equivalent to the DOR.

Substantial uncertainties exist in the various bases for developing conservation measures for the

Covered Activities, and to the extent these uncertainties show themselves in unplanned ways that

affect the ITP during the term of the ITP, they may or may not constitute Changed

Circumstances. The range of some of these uncertainties and their implications for this HCP are

addressed in the next subsection. Then, the next following subsection focuses on specific

uncertainties that the District has committed to address as Changed Circumstances, each with a

specific proposed response by the District intended to confirm and, as possible, remedy the

circumstance.

7.2.1 Considering the Range of Uncertainties

A number of issues and uncertainties could create Changed Circumstances, including the

uncertain existence and magnitudes of various factors that could affect the ITP, HCP

effectiveness, or that are not otherwise quantifiably taken into account in the District HCP.

Under the District HCP, District staff will continue to monitor and to develop new information

that will address and resolve known issues, clarify others, reduce uncertainties, and mitigate

impacts associated with the Covered Activities; and consult with the Service as warranted to

evaluate the need for amendments to the HCP and ITP. The following subsection identifies the

more important issues and uncertainties and their possible effects and impacts, without

attempting to characterize or evaluate them in detail.

7.2.1.1 Global Climate Change: Effects and Probabilities

Probably the largest uncertainty that may substantively affect the long-run effectiveness of the

District HCP measures relates to “climate change” in the larger sense. The uncertainty isn’t

related to whether climate change is now occurring. As described in EARIP (2012),

The U.S. Climate Change Science Program (CCSP) has concluded that the global

climate is changing. Effects of this change on the existing environment have been

evaluated in a 2008 U.S. national scientific assessment (National Science and

Technology Council, 2008) which integrates, evaluates, and interprets the findings of

the CCSP and draws from and synthesizes findings from previous assessments of the

science, including reports and products by the Intergovernmental Panel on Climate

Change (IPCC).

The conclusions in the National Science and Technology Council assessment build on

the vast body of observations, modeling, decision support, and other types of activities

conducted under the auspices of CCSP and from previous assessments of the science,

including reports and products by the IPCC, CCSP, and others. This assessment and

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the underlying assessments have been subjected to and improved through rigorous

peer reviews. According to CCSP’s Synthesis and Assessment Product (SAP) 4.3

(Backlund et al., 2008), it is very likely that temperature increases, increasing carbon

dioxide levels, and altered patterns of precipitation are already affecting U.S. water

resources, agriculture, land resources, biodiversity, and human health, among other

things. SAP 4.3 also concluded that it is very likely that climate change will continue

to have significant effects on these resources over the next few decades and beyond.

The IPCC has also determined that warming of the global climate is unequivocal, and emissions

of greenhouse gases emitted by humans are largely responsible for the warming over the past

100 years (IPCC, 2007b, 2013). In the future, the net global effect of the warming, even if no

additional greenhouse gases are emitted, will be increased precipitation, though with variable

spatial distribution and intensity. Extreme weather events, such as heat waves, flooding, and

drought, will continue to increase in frequency and intensity, as well as adverse impact (IPCC,

2007b, 2013; USGCRP, 2014).

The uncertainties arise as to what that means for the HCP region generally and for the Covered

Species particularly. The Summary for Policy Makers prepared by the IPCC (2007b, reinforced

in 2013) suggests there is high confidence (eight out of ten chances) that drought and flooding

will be both more severe and frequent, and those conditions will have mostly negative

consequences for ecosystem structure, function, inter-species interactions, and therefore

biodiversity. It includes more detailed predictions of long-term changes in precipitation patterns,

at both global and regional levels (IPCC, 2007a). The impacts that have been predicted for

Central Texas, according to one model (A1B), would result in a 10–20% reduction in

precipitation during the winter months by 2090–99, relative to 1980–99 conditions; but no clear

trend in the direction of change for precipitation during the summer months by 2090–99. These

slight and variable differences are reflected in Figure 7-1 from modeling of these data by the

Nature Conservancy (Maurer et al., 2007), which shows the sensitivity of precipitation

projections by this model to emission scenarios, especially in Central Texas.

Joseph Alcamo, a lead author of many IPCC publications on climate change and water resources,

has developed and applied another global water model to analyze the impacts of climate change

and socio-economic driving forces on future global water stress, derived from the A2 and B2

scenarios of the IPCC (Alcamo et al., 2007). The investigators define “water stress” as the

intensity of pressure put on water resources and aquatic ecosystems by external drivers of

change. The principal cause of increasing water stress, where it occurs, is increasing water

withdrawals. Alcamo and other investigators show increases in water stress for the Central

Texas region of between 50% and 100% by the 2050s, under two different IPCC scenarios (A2

and B2). This work and other more local, as well as large-scale, scenarios indicate that

significant additional challenges and competition for water, and correspondingly less water

availability for wildlife and other instream functions, must be anticipated and confronted.

The uncertainty in climate change effects on local precipitation has been underscored by

Nielson-Gammon (2011), who noted that observed variations in precipitation over the past

century in Texas are larger than most future climate projections of precipitation changes by mid-

century.

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Figure 7-1: Change in annual precipitation projected over Texas by mid-century. Changes based on the median of models used in the IPCC Fourth Assessment and the A1B emissions scenario

(medium) on the left and the A2 (high) on the right. Areas in darker shades of green are projected by half the models

to increase and areas in yellow and lighter shades of green are projected by half the models to decrease (Maurer et

al., 2007).

Nevertheless, governmental agencies and other organizations that participate in water-resource

planning are either currently planning for the potential changes due to climate change, or they

intend to incorporate that into future planning. Hirsch (2008) recommended the following

approach to water-resource managers: (1) collect more data, (2) consider paleoclimate records,

(3) keep an eye on climate science and change, and (4) don’t lose sight of other stresses (for

example, population and demand, urbanization, return flows, etc.).

7.2.1.2 Effects of Climate Change on Regional Groundwater Systems and

Aquifer

A growing consensus among climatologists suggests that the next 50 years is likely to be

warmer and drier in the HCP Planning Area than the previous 50 years (Seager 2007a,

2007c), especially if anthropogenic climate changes continue to accelerate, but also even if

atmospheric carbon dioxide concentrations stay at current levels (Seager et al., 2007a):

According to research compiled by the IPCC, from 1970 to 2004, much of the region

that includes Central Texas has encountered a warming trend on the order of 0.2-

1.0°C (IPCC, 2007a). The IPCC findings include new and stronger evidence of

observed impacts of climate change on unique and vulnerable systems, with

increasing levels of adverse impacts as temperatures increase further. An increasing

risk of species extinction is projected. Confidence has increased that a 1 to 2°C

increase in global mean temperature above 1990 levels (about 1.5 to 2.5°C above

pre-industrial levels) poses significant risks to many unique and threatened systems

including many biodiversity hotspots.

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While Global Circulation Models (GCMs) are a key tool for predicting and analyzing climate

change, and regional predictions for Texas are reported (Seager, 2007), GCMs are not yet useful

enough for predicting and assessing impacts in regional areas such as Texas. For example,

rainfall is a key variable to assess environmental impacts (Leung, 2008). However, rainfall

predictions from GCMs have the lowest confidence of simulated results and a lot of variability.

Most GCM models suggest a “general drying” for Texas (Washington, 2008), but this is not

consistent with regional rainfall and stream flow trends in Texas (Hunt et al., 2012b; Nielson-

Gammon, 2008; Singh, 2008; Leung, 2008). In the last 30 years, Texas has been warming faster

than the global average, has been unusually wet, and has experienced extreme events that likely

will continue to happen in the future (Nielson-Gammon, 2008; North, 2008).

Texas will get hotter and climate change will exacerbate stresses already imposed upon water

resources (Hayhoe, 2008). Climate in Texas continues to change, although impacts from those

changes have not been observed as they have in the U.S. Southwest such as Arizona

(Woodhouse, 2008). Generally, it is expected that rapidly responding aquifers such as the

Edwards Aquifer will be more sensitive to changes in climate (Mace, 2008). However, no trends

have been observed in recharge since the 1930s for the San Antonio segment of the Edwards

Aquifer (Loaiciga, 2008). A study of hydrologic and hydrogeologic responses by Hunt et al.,

(2012b) in Central Texas concluded that, while there has been an overall increase in the amount

of water in water budgets of various stream systems, the base flows of streams and springflows

have slightly decreased over the past several decades since the DOR, likely owing to increased

use of groundwater resources (Hunt et al., 2012b). This is particularly relevant to poorly

controlled withdrawals from the Trinity Aquifer up-gradient from the ITP Area, which tend to

result in lower base flows and flows of shorter duration in the creeks that contribute recharge to

the Aquifer. But a study of global warming impacts on the San Antonio segment of the Edwards

Aquifer by Chen et al. (2001) predicts that annual temperatures will rise (~3°F) and annual

rainfall will decrease (~4 in) by 2030 resulting in a 20% decrease in recharge during droughts.

However, these effects and their impacts are uncertain. Increasing demand due to population

growth and rising temperatures will be the dominant factors impacting springs and water

availability (Mace, 2008; Loáiciga, 2008). It seems clear that climate change will likely

exacerbate these impacts, and vice versa.

As summarized in the EARIP (2012),

“Climate change could impact groundwater resources by affecting recharge,

pumping, natural discharge, and saline intrusion (Mace and Wade 2008). They

suggest that climate change will more adversely affect karstic aquifers (like the

Edwards Aquifer) that recharge locally from streams and rivers in comparison

to aquifers where effective recharge is increased through pumping and the

capture of intermediate and local groundwater flow paths. A warmer, dryer

climate will increase demand for water to support agriculture, municipal, and

industrial use. This will result in greater demand for both surface and

groundwater. Decreases in surface-water supply due to climate change may also

increase demand for groundwater use (Kundzewicz et al., 2007; Mace and

Wade 2008). Natural aquifer discharge to springs and seeps is affected by

recharge to the aquifer, discharge by pumping, and changes in groundwater

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gradients as affected by plants, including phreatophytic species that demand

higher amounts of water.

Mace and Wade (2008) and Loáiciga et al., (1996) suggest that the Edwards

Aquifer is probably Texas’s most vulnerable aquifer and groundwater resource

with respect to climate change and variability and if there is a long-term drying

of the climate in south-central Texas, area groundwater users can expect to be

under more frequent drought restrictions.

Loáiciga et al., (2000) studied the climate change impacts on the Edwards

Aquifer. Climate change scenarios were created from scaling factors derived

from several general circulation models to assess the likely impacts of aquifer

pumping on the water resources of the Edwards Aquifer. Aquifer simulations

using GWSIM IV indicate that, given the predicted growth and water demand in

the Edwards Aquifer region, the aquifer's groundwater resources appear

threatened under 2×CO2 climate scenarios. Their simulations indicate that

2×CO2 climatic conditions could exacerbate negative impacts and water

shortages in the Edwards Aquifer region even if pumping does not increase

above its present average level. The historical evidence and the results of this

research indicate that without proper consideration to variations in aquifer

recharge and sound pumping strategies, the water resources of the Edwards

Aquifer could be severely impacted under a warmer climate.”

It is possible that progressive increases in the ambient atmospheric temperature in Central

Texas would lead to seasonal or year-round increases in the temperature of springflow at

Barton Springs, possibly causing increased stress and vulnerability to disease for the

salamander species there and possible reductions in DO saturation levels. Such temperature

increases could be moderated to some unquantifiable extent by the long residence time of

groundwater flowing from the Aquifer, especially during severe drought. It is also possible

that any reduction in long-term average precipitation in Central Texas during winter could

result in reduced storage in the Aquifer at the onset of spring and summer when water losses

through natural processes and human activity increase. Such a condition could also

exacerbate the reduction in summer springflow during droughts.

Although the State of Texas mandates use of the DOR for water-planning purposes, the DOR

may not represent the worst-case condition that actually could occur in the ITP permit period

(Cleaveland, 2006; Nielsen-Gammon, 2008; Woodhouse, 2008; see also Section 7.2.1.3,

Ecological Significance of Paleoclimate Indications). Put another way, it is possible that the

DOR could occur with higher frequency than history indicates. Under such circumstances, the

sustainable yield of the Aquifer could be somewhat less than that indicated by modeling, and the

lowest expected flows at Barton Springs could be lower, other factors being equal. On the other

hand, the DOR has been estimated to have a recurrence interval about five times longer than the

20-year duration of the District HCP, as described in Section 4.2, Requested Permit Duration.

These factors suggest that a recurrence of a drought causing Barton Springs flow to diminish to a

level lower than has ever been recorded during the course of the ITP permit period is not likely.

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Nevertheless, taken together these are trends for which additional attention and concern are

warranted. There is a finite, although indeterminate, likelihood that an extreme record event

would occur during the term of the ITP, and that the likelihood, although probably small, will

increase under recent climatic trends to some indeterminate degree.

7.2.1.3 Ecological Significance of Paleoclimatic Indications

Tree-ring studies and stable isotopic evidence suggest that the part of the North American

continent containing the study area has experienced much more severe (especially longer)

droughts than the DOR during medieval times and even in prerecorded history (for example,

Cleaveland et al., 2006; Seager et al., 2007b, 2007c). It is not known whether or how many

times Barton Springs has stopped flowing over the course of several millennia. Yet the

salamanders at Barton Springs have somehow survived. The District HCP is based on a premise

that extremely low flow or no flow at the Barton Springs outlets could jeopardize the continued

existence of the species; but whether that premise is true is unknown. The size and distribution

of the Covered Species populations before the historic and prehistoric droughts are unknown, so

it is not known if the populations are particularly persistent or are the last surviving remnants of

much larger populations. Clearly the additional stresses contributed by cultural factors in the last

century (for example, increased impervious cover and urban storm runoff) distinguish current

and future responses from those of historic or prehistoric periods.

7.2.1.4 Lack of Water Chemistry, Water Quality, and Flow Data to Calibrate

Models During Extreme Low Springflow Conditions

Modeling to predict springflow conditions as described in Section 3.2.2.1.2, Sources and

Implications of Variation in Springflow at Barton Springs, like any modeling exercise, yield

outcomes of predicted springflow that are not absolute. Rather, they are theoretical, predicted

estimates affected by the limitations and accuracy of the model, quality of input data, and major

assumptions. Therefore, analyses of predicted springflow in the HCP are limited to evaluation

and comparison of alternative groundwater management strategies in a broad sense, not in a

precise replication of a future scenario that is indeterminate.

The lowest recorded flow at Barton Springs is just under 10 cfs (0.28 m3/s), which occurred

during a period when little groundwater was being withdrawn from the Aquifer. Thus, no data

are available to verify the relationship between predicted or modeled flow and water chemistry

for flows less than 10 cfs. In fact, almost all information about the relationship between flow

and water chemistry comes from flows that are no less than about 14 cfs (0.40 m3/s).

Accordingly, extrapolation of trends in flow, chemical components, and their relationships to

flows less than 14 cfs is problematic. It is not known, for example, whether DO concentration

continues to decrease as flow decreases or whether it “plateaus” at some small sub-saturated

concentration. Water temperature, even though it varies over a relatively small range in the

Aquifer, may affect DO concentration of springflow independent of springflow and water levels,

as it relates to DO saturation (Mahler and Bourgeais, 2013). These same investigators note that

critically low DO concentration can be caused by recharge from stormflow, especially during hot

months. It is also not known whether and at what rate flow continues to decrease under

prolonged Extreme Drought, or plateaus as a result of induced recharge of water that would

remain in the larger and topographically higher San Antonio segment under more normal

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conditions. A statistical analysis of correlations between DO concentration and springflow

between 1993 and 2011 by the COA may indicate a minimum DO concentration under ambient

conditions that could be as high as 3.5 mg/L or as low as 0 mg/L (City of Austin, 2013).

Although the COA has reasonably inferred a worst-case scenario, there currently is no

unequivocal basis for reliably projecting the DO concentration at extremely low flow.

7.2.1.5 Cumulative Negative Effect of Pollutants in Groundwater Discharges

on Salamanders

In development of the District HCP, studies funded by the District have focused on the

relationship of DO concentration and specific conductance with toxicity and other adverse

effects on the Covered Species. Of these parameters, DO concentration and springflow are

believed to be controlling. However, the Service recently has suggested that specific

conductance, indicative of the relative salinity of discharging groundwater, may also be

important, especially to eggs and larvae (Service, 2013b); however, it is not known if the

relatively small increases in salinity at low flows produce adverse effects. Springflow is

presumably correlated with flow velocity in the habitat zones near the spring outlets, which in

turn may be correlated with oxygen exchange potential across salamander gills (which is

potentially important during periods of depressed DO concentration). Changes in DO

concentration and salinity (and water temperature) are variations of the natural system unrelated

to pollutants; but pollutants may produce adverse effects either on their own or in combination

with changes in natural water chemistry.

Little information exists in the biological literature on impacts of other chemical constituents and

physical conditions to the Covered Species. But nonpoint-source pollution in the Contributing

and Recharge Zones of the Aquifer is already increasing the amount of anthropogenic pollutants

like pesticides, domestic wastewater from decentralized and centralized treatment facilities,

fertilizers and other nutrient sources, other oxygen-demanding constituents such as pet waste,

suspended sediment, and some heavy metals in springflow (Mahler et al., 2011). Concentrations

of those pollutants are likely to increase with time along with development, as additional

volumes of treated domestic wastewater (sewage) and its oxygen-demanding waste loads are

discharged directly and indirectly to streams that recharge the Aquifer. However, Mahler and

Bourgeais (2013) suggests that there has been more recently a trend toward increasing DO

concentration overall in the Aquifer, indicative of the complex controls on this parameter.

There has been no attempt in this HCP or in any other investigation to assess the impacts of

different concentrations and mixes of water quality pollutants or their possible adverse impacts

on the Covered Species, primarily owing to the vulnerability of the Covered Species. Because

management of land use and associated development that generates pollutant loads are beyond

the authority of the District and the scope of its programs, land use and associated development

are therefore not proposed for management or research under the District HCP.

7.2.1.6 Response of Salamanders to Variations in Habitat Condition

By necessity, status of the Covered Species’ populations is based on counts of observable

individuals at the spring outlets and in spring runs. Low counts clearly are associated with

stress-related impacts, including population declines (City of Austin, 2013). As noted in Section

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5.1.2.1, Distribution of] Barton Springs Salamander, it has been suggested by experts that

salamanders appear to be able to migrate locally to areas of less stress in the Aquifer and in

spring runs during certain periods, to an unknown extent. It seems reasonable that migration into

the Aquifer and even to and from Main Springs is partly responsible for the observed rapid

increase of the salamander population at Upper Barton Spring when that outlet starts flowing

again after many months of no flow and no observable salamanders during the earliest stages of

drought. On the other hand, during severe, prolonged drought conditions, the populations of

both Covered Species at Old Mill Spring outlet decrease substantially to no or just a few

individuals after extremely low flow at the outlet. Those very low observable numbers persist

for months to years, even with re-establishment of some springflow.

The difference in behavior of these two populations and their ability to accommodate drought

may be related to known differences in hydrogeologic conditions at the outlets. Such differences

may be associated with the amount of subsurface migration that is possible. For the subterranean

Austin blind salamander especially, low observable numbers during prolonged and/or severe

drought may not be an indicator of mortality, although some population decrease during such

periods of DO stress is reasonably expected. But the areal extent and proportional amount of

such migration and their differences for either species, while inferred to occur, are largely

unknown. These factors confound the quantitative interpretation of salamander reactions to

stress and population impacts. These uncertainties probably reduce the reliability of stress and

quantitative take estimates determined on the basis of counts. However, no other deterministic

approach currently exists.

Other, more hydrologic uncertainties may relate to migration. Most natural discharge from the

Aquifer occurs at Barton Springs. However, smaller springs have been noted that flow directly

into Barton Creek, upstream from Upper Barton Spring and also into the Colorado River. The

springs upstream from Upper Barton Spring only discharge under moderate-to-high flow

conditions. Some small springs (for example, Cold Springs) are visible on the south shore of

Lady Bird Lake at the water level of the lake. Other discharges into the riverbed but below the

lake level are also possible, but they are difficult to discern either by direct observation or by

monitoring temperature differences in the lake. The elevation of the lowest point in the Colorado

River near the confluence with Barton Creek is about 412 ft msl. The elevation of the main

discharge point at Main Springs is about 420 ft msl. Thus there is the potential for Aquifer

discharge into the Colorado River owing to the elevation difference between the spring outlets

and the base level of the river (TWDB, 1999). Although the presence of small springs below the

lake level is unproven and would likely be only a very small component of the water balance for

the aquifer as a whole, the conceptual model of the aquifer suggests that there are numerous

small pathways for flow along faults, fractures, and bedding planes (surfaces that separate

successive rock units or layers). Geologic mapping in the vicinity of Barton Springs shows that

there are about six major faults that extend to the Colorado River between the downstream end of

Barton Creek (confluence with the Colorado River) and Cold Springs. Fractures are common at

outcrops of various Edwards Aquifer rock units. It is likely that small discharges occur where

these faults, fractures, and bedding planes intersect the riverbed. Such discharges into the

Colorado River may occur even with no flow at the major spring outlets. They may offer

alternative groundwater flow paths and therefore possible flow environments with sufficiently

high water velocities to support the salamander ecosystem. However, this is hydrogeologically

informed conjecture at this point, as no studies have been done to address this uncertainty in

subsurface flow environments and suitability and use as habitat of the Covered Species.

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In addition, the conceptual model used by the District for the take estimate is that the spring

outlets are hybrid springs, where water from both confined and unconfined parts of the Aquifer

discharge. The relative proportion of flow from each of those parts of the Aquifer varies with

time and differs among outlets. The unconfined parts of the Aquifer provide access for

salamanders from the outlets to conduits and fissures at the water table (which is in contact with

the atmosphere and provides a source of re-aeration within the Aquifer) and likely characterize

the subterranean-only habitat of the Austin blind salamander. However, this is simply

hydrogeologically informed conjecture at this point, as no studies have been performed to

address this uncertainty in subsurface flow environments and suitability and use as habitat of the

Covered Species.

7.2.1.7 Recent Texas Court Decisions and Aftermath

In a series of decisions, culminating in the EAA v. Day opinion in 2012, the Texas Supreme

Court has now clarified that "groundwater in place" below the surface of the land is real property

owned by the owner of the surface estate. It follows from the Court’s decision that as real

property, it is severable from the land and may be sold separately, although no specific amount

of owned groundwater can be inferred a priori. Further, the Court has determined that, even

though its withdrawal is subject to reasonable and equitable regulation by a GCD, a GCD’s

regulation that arguably produces an inequitable or unfair economic burden on a landowner with

investment-backed expectations may outweigh the public interest in managing groundwater and

is potentially regulatory “taking,” subject to compensation.

Moreover, a recent appellate court ruling, in EAA v. Bragg, suggests that even rational, well-

considered groundwater regulation may in fact be a taking for which the regulating GCD is

financially liable. The assessment of compensable takings will be determined by future

legislative action and judicial opinions, including likely appeals to the Texas Supreme Court.

Although the actual implications of these decisions for the District’s operations are almost

certainly to be elaborated further during the term of this HCP and ITP, it represents a new factor

in the authority with which the District, or any GCD, may be able to limit groundwater

withdrawals without putting its financial resources at risk. If it is ultimately decided that the

District can be held financially liable for regulatory takings, it is not clear whether such a

fundamental change in the District’s regulatory capability is a Changed Circumstance or an

Unforeseen Circumstance for its HCP or, alternatively, a basis for suspension or termination of

the ITP by the Service. Ultimately the Service will be expected to make the determination of

what sort of HCP circumstance exists for that eventuality, which will in turn define the role and

response of the District in accommodating that circumstance.

7.2.2 Considering and Responding to Changed Circumstances

Although the District believes that the initial measures to be funded by the District HCP will be

effective in conserving habitats and the Covered Species, it is anticipated that conditions within

the aquifer, the status of habitats, and the overall condition of the species over time will change.

In addition, it is likely that additional and different conservation measures, not contained in the

District HCP, will be suggested and be proven to be effective during the term of the District

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HCP. Finally, measures currently funded by the District HCP may prove to be ineffective to

conserve either the species or the habitats in which they dwell. These situations potentially

constitute Changed or Unforeseen Circumstances. Therefore, the District is proposing to

monitor and gauge the effectiveness of existing conservation measures on an ongoing basis; to

evaluate alternatives in accordance with the monitoring reporting in Section 6.3.2 (General

Performance Metrics and Reporting) and the adaptive management processes in Section 6.4

(District Adaptive Management Process); and to propose modifications, additions, or alternative

conservation measures that could be implemented or supported by the District within its

regulatory purview, including dealing with different circumstances as described below.

Events or situations likely to occur or that could be reasonably anticipated during an average 20-

year period and to affect the ITP would be considered “Changed Circumstances.” Events not

reasonably expected to occur, or anticipated to occur less frequently than once during an average

20-year period (such as a drought worse than the DOR) would be considered “Unforeseen

Circumstances.” For Changed Circumstances reasonably related to the Covered Activities and

the proposed conservation measures in the District HCP, the District includes in this section a

specific proposed response plan, in keeping with 50 CFR §17.22(b)(5)(i) for such Changed

Circumstances. Except as noted in the subsections below, the contingency actions described as

part of the response plan are able to be implemented within the funding commitments of the

District discussed in Section 8, District HCP Funding Assurances, by reprogramming internal

labor of District staff and/or certain contracted support.

7.2.2.1 Changed Circumstance: Listing of New Species Not Covered by HCP,

or Recognition of Substantial Differences in the Characteristics and Spatial

Distribution of Habitats of Covered Species

The listing of a new species by the Service as threatened or endangered within the ITP Area that

is not covered by the District HCP may constitute a Changed Circumstance. The two ecoregions

of the HCP Planning Area have numerous vulnerable aquatic and terrestrial species (see

Appendix A for a current listing), but none of those vulnerable species (or others) are known to

exist in the ITP Area. The Service is statutorily required to notify the District and/or publish

notice in the Federal Register upon becoming aware that a species associated with the habitats in

Barton Springs and not a Covered Species (but rather an “Uncovered Species”) that may be or

has been proposed for listing.

The recent identification of the far-field habitat and its recognition by the Service suggest that

substantially more information on these habitats may be developed during the term of the ITP,

which may portend changes in the size(s) of the Covered Species and/or the amount of take.

Similarly, the spatial distribution of the Covered Species may be further elucidated with

continuing and new investigations of their habitat. These may constitute Changed

Circumstances.

Proposed Response:

a. Upon receipt of notice of the listing of an Uncovered Species or scientifically credible and

specific documentation of changes in the relevant characteristics of the habitat of the

Covered Species, the District will seek to partner with the Service regarding confirmation of

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this circumstance as a Changed Circumstance for the District HCP as determined by the

Service, and the necessity of modification and amendment of the District HCP. If the

District elects to pursue amendment of the applicable permit, the District will ask the Service

to provide technical assistance to the District in identifying any modifications to the District

HCP warranted by the Changed Circumstance and necessary to amend the applicable federal

permit.

b. The District shall assess the efficacy of the conservation and mitigation measures as already

provided in the District HCP as they provide for avoidance, minimization, and mitigation of

take of the Uncovered Species, and provide that analysis to the Service.

c. The District shall seek guidance from the Service in determining whether any further

conservation or mitigation measures are required and whether the Covered Activities

described in the ITP would require an amendment to authorize any incidental take of such

Uncovered Species.

d. The District shall provide the Service with an assessment of whether the District’s Covered

Activities and the proposed response to the listing of the Uncovered Species will adversely

affect take of Covered Species, consistent with Section 10 of the Act.

e. If the assessment finds there is an adverse effect on take of the Covered Species and the

Service concurs, the District will request a specific amendment to its HCP and ITP. Upon

amendment, the District will incorporate any needed conservation measures that are within

its regulatory authority and financial capability. The District will consult with the Service on

whether a revised NEPA document is required to complete an amendment of the HCP.

7.2.2.2 Changed Circumstance: Unexpectedly Larger Adverse Effects on

Springflow Characteristics and on the Covered Species During Severe

Drought In the ITP Term

As identified and discussed in this HCP, there are substantial uncertainties as to effects and

unquantifiable impacts associated with the Covered Activities and the habitat of the Covered

Species, especially during severe drought conditions. For example, it is conceivable, though not

currently considered likely during the term of the ITP, that:

• the frequency of severe droughts or the severity of a drought of a given frequency,

including a recurrence of the DOR, could be more adverse than projected:

• springflows at all outlets and/or at individual outlets during very prolonged severe

droughts could produce smaller (or no) springflows than considered herein: or

• drought and non-drought springflows could be accompanied by sustained DO

concentrations related to springflows that were substantially different and/or significantly

more adverse to the Covered Species, including their individual life stages, than now

anticipated.

The HCP utilizes knowledge that has been developed over more than a decade from existing

data, models, laboratory and field investigations, and inferred relationships by many researchers.

The “best science” that is unequivocal and non-speculative has been incorporated within this

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Plan. But within the bounds of current knowledge, the magnitude and consequences of some

potential adverse effects on the habitat of the Covered Species are presently indeterminate or

unquantifiable with certainty. Accordingly, some adverse conditions that arise will first be

reasonably evaluated by the District and the Service as to whether they should be considered

Unforeseen or Changed Circumstances.

However, it is also possible that severe drought during the term of the ITP could suddenly be

accompanied by degradation of the habitat substantially more than anticipated in this HCP on a

shorter-term, rapid-onset basis, and in a way that has immediate and more adverse consequences

for the Covered Species or for a life stage of the Covered Species than was addressed in this

HCP. This circumstance would be considered a Changed Circumstance. It would be associated

with a persistent, declared Stage III-Critical or more severe drought condition, indicating the

likely relationship of DO concentration to springflow, and would be triggered by confirmed

mean DO concentrations in the outlets of Main Springs and/or Eliza Spring less than 3.4 mg/L,

the laboratory LC50, for more than one month, which would otherwise be unexpected. The

frequency of such DO measurements would increase to daily (or continuous) under the terms of

the proposed ILA between the COA and the District, should such a circumstance develop, to

elucidate the persistence and confirm the likely causes of the suddenly depressed DO. Such a

scenario would eliminate transient and non-springflow-related causes of low DO concentrations

in flows not materially related to the Covered Activities, such as substantial spills or leaks of low

DO and/or high oxygen-demanding substances in the springshed that could produce highly

variable but short-term effects on the DO regime.

Proposed Response:

Following consultation with the Service as to a) whether a particular unexpected change creating

concern is a Changed or an Unforeseen Circumstance, and b) whether there is the need for

immediate and extraordinary mitigation to reduce take and avoid jeopardy, the District Board

could provide one or both of two sequential responses:

a. If the DO Augmentation Project, developed as a Mitigation Measure (see Section 6.2.2.2,

Mitigation Measures) proved feasible and had been implemented in its planned stand-by

mode at the time of this circumstance, the Board would trigger its implementation under the

terms of its Interlocal Agreement with the COA. The District and the COA would then

continue to monitor DO concentration in the outlets of Main Springs and Eliza Spring at least

daily or continuously until the extraordinary stress on the species is relieved, as indicated by

weekly average DO concentrations in flows from those outlets greater than 4.5 mg/L, the

NOAEL, on a sustained basis.

b. If the DO Augmentation Project could not be implemented for any reason or failed to provide

the intended benefit to springflow, the Board is committed to induce selected individual

permittees that have unused alternative water supplies to voluntarily agree to temporary

withdrawal curtailments greater than otherwise required by District Rules. These

curtailments would continue until the extraordinary stress on the species is relieved, as

indicated by weekly average DO concentrations in the outlets of Main Springs and Eliza

Spring greater than 3.7 mg/L, the laboratory-based LC25, on a sustained basis. The

inducement for such temporary curtailments could be temporary increases in the permittees’

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permitted volumes once drought ends. This provision would require a change in the

District’s Rules but not its MP, to be initiated upon ITP approval for ready implementation.

The District will then continue its consultation with the Service to assess what, if any, changes in

the HCP conservation measures and in the ITP provisions are indicated, and upon concurrence

make those changes that are within its authority and financial capability.

7.2.2.3 Changed Circumstance: Substantial Change in Statutory, Legal, or

Financial Means to Execute Conservation Measures According to ITP

A change in the District’s legal authority or a substantial reduction in the level of annual

revenues available to the District for implementation of the District HCP may constitute a

Changed Circumstance. The District depends on annual revenues from usage fees derived from

production permits, based on statutory authority granted by the Texas Legislature, and also from

prescribed contributions by the COA under a statutory mandate. These revenues may vary

somewhat each year, as explained in Section 8, District HCP Funding Assurances, and they are

not anticipated to be curtailed or terminated during the course of the ITP; but neither are they

guaranteed sources or amounts of revenue. GCDs are currently the Legislature’s preferred

means of managing groundwater, but the scope of this authority is subject to both legislative

pressures and constitutional challenges in court. It is foreseeable that during the term of the

HCP, legislative changes could affect both the District’s legal authority and its level of annual

revenues; and legal defense expenses, such as noted in subsection 7.2.1.7, Recent Texas Court

Decisions and Aftermath, could adversely affect the District’s financial condition. However, the

District maintains funds in a contingency account to provide protection from emergency

conditions affecting its revenues or expenses, and it will use them as needed to maintain the

necessary funding of conservation measures and other ITP requirements.

Proposed Response:

If the District’s statutory authority was substantially reduced, or its normal annual revenues were

curtailed by more than 25 percent, or its non-labor-related expenses net of capital expense

increased by more than a factor of 1.5 in any 2-year period (but not to a level at which the

District would be unable to maintain the funding levels specified in the District HCP), the

District will notify and enter into consultation with the Service. The purpose of the consultation

would be to analyze the efficacy of continuing the HCP conservation measures and their impact

on proposed take of the Covered Species, prioritize alternative response measures, and resolve

the Changed Circumstance as it relates to take. Such a circumstance would not be triggered by

drought and low springflow, so it may not be associated immediately with take issues, rather

changes to take in the future. Possible responses could include reducing the term of the ITP,

and/or changes to the amount of incidental take exempted under the ITP. Coordination between

the District and the Service would be required and the outcome would be either a major or minor

amendment to the ITP.

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7.2.2.4 Other Changes in Circumstances

Other changes in circumstances are foreseeable and might affect the status of the Covered

Species. For example:

• Intentional, illegal human activities (for example, vandalism; terrorism) that are destructive

to the Covered Species and/or their habitat.

• Major accidental pollution in the ITP Area (for example, toxic chemical spills; wastewater

spills; petroleum and petrochemical pipeline leaks) that is destructive to the Covered Species

and/or their habitat.

• Acute effects from increased pollutant discharges from either point sources, nonpoint

sources, or both.

• Floods, erosion, and sedimentation of Barton Creek that, via a single event or by cumulative

effect, degrade the health of the Covered Species or adversely change the quality of their

habitat throughout a substantial part of their distribution.

• Changes in factors other than physical conditions and non-living resources that affect

organisms (for example, increased predation and inter-species competition that alter

ecological conditions.)

• Decreased recharge to the Aquifer arising from smaller base flows in the creeks in the

Contributing Zone over time, owing to the effects of climate change and especially the

impacts of withdrawals up-gradient that reduce the amount of groundwater from the Trinity

Aquifer discharging to those streams.

• Alternative water-supply benefits in the form of prospective reduced withdrawals from the

Aquifer are not realized.

However, unlike other changes identified in the subsections above, these changes are not related

to the Covered Activities, and the District is not able to address them directly as they are not

within the statutory authority of the District; nor does the District have the financial resources for

their remediation or even evaluation. Accordingly, these are not considered Changed

Circumstances for the District HCP, and no specific contingency plan is provided in this HCP as

part of the proposed response to other changes.

Proposed Response:

Should events or changes such as these occur, following notification by the District to the

Service, each will be evaluated jointly by the District and the Service as to significance to the

Covered Species and confirm whether or not they are, in fact, Changed Circumstances and

circumstances that the District is able to address under its AMP processes. It is also anticipated

that the District will coordinate with the COA in making such evaluations, as the changes could

represent Changed (or Unforeseen) Circumstances under the Barton Springs Pool HCP as well.

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7.3 Unforeseen Circumstances

The Service defines the term “Unforeseen Circumstances” to mean “changes in circumstances

affecting a species or geographic area covered by [an HCP] that could not reasonably be

anticipated by plan developers and the Service at the time of the HCP’s negotiation and

development and that result in a substantial and adverse change in the status of the covered

species” (50 CFR §17.3). Such circumstances are not “unimaginable,” just not reasonably

expected during the term of the ITP. Unlike identified Changed Circumstances, the Service

rather than the Applicant (the District) is responsible for Unforeseen Circumstances and

responding to them

7.3.1 Determining Occurrence of Unforeseen Circumstances

In making the determination that such an event constitutes an Unforeseen Circumstance, under

its statutory obligations the Service will consider, but not be limited to, the level of knowledge

about the affected species and the degree of specificity of the species conservation program

under the District HCP. The Service also will consider whether failure to adopt additional

conservation measures within the District’s regulatory authority and financial ability would

appreciably reduce the likelihood of survival and recovery of the affected species in the field.

In making a determination regarding the occurrence of any Unforeseen Circumstance, the

Service has developed and will follow the procedures set forth in its applicable regulations (50

CFR 17.22(b)(1)(iii)). These are summarized below, but the statutory language is controlling.

Notice to Applicants and Participants

The Service shall provide written notice to the District together with a detailed statement of the

facts regarding the Unforeseen Circumstance involved, the anticipated impact thereof on the

Covered Species and its habitat, and all information and data that support the allegation. In

addition, the notice shall include any proposed conservation measure(s) believed to address the

Unforeseen Circumstance, an estimate of the cost of implementing such a conservation measure,

and the likely effects upon (a) the District and its permittees, and (b) the existing plans and

policies of any involved federal or state agencies.

Responses as a Result of New Information Derived Through Adaptive Management

The research and investigative measures that the District commits to undertake as a part of its

adaptive management efforts may indicate or otherwise call for specific other responses to

Changed or Unforeseen Circumstances. As new information is obtained during the course of the

ITP period and in consultation with the Service, the District and the Service may agree to modify

or redirect existing conservation measures to mitigate the effects of Unforeseen Circumstances,

within the scope of existing approved and funded conservation actions and ITP terms. To the

extent that these modified or redirected conservation measures do not affect conservation of

other species or habitats, this approach may be deemed an adequate response to the Unforeseen

Circumstance. However, if the proposed modifications or redirected conservation actions could

affect the conservation of another Covered Species or its habitat, the procedure outlined below

will be followed.

Submission of Information by Others

The District shall have a meaningful opportunity to submit information to the Service and shall

do so within 60 days of the written notice, as provided above. Upon the written request of the

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District or any other participant in the District HCP, the time for submission of said information

may be extended by the Service.

District Review

Within 90 days after the close of the period for submission of additional information, the District

shall assess (a) the alleged Unforeseen Circumstance, (b) the proposed additional conservation

measure(s), (c) its effects upon the Covered Species and its habitat and the economy and

lifestyles of the District and permittees, and (d) possible alternatives to the proposed additional

conservation measures that would result in the least adverse impacts upon the economy and

lifestyles of the District and permittees, while at the same time leading to the survival and

recovery of the Covered Species.

Findings

The Service has the burden of demonstrating that an Unforeseen Circumstance has occurred, and

that such Unforeseen Circumstance is having or is likely to have a significant adverse impact on

Covered Species or its habitat. The findings of the Service must be clearly documented and be

based upon the best scientific and commercial data available regarding the status and habitat

requirements of the species. In addition, based on the results of its own expedited analysis of the

Changed or Unforeseen Circumstance and the information provided by the District or other

participants in the District HCP, the Service must provide the justification and approval for any

reallocation of funds or resources necessary to respond to the Unforeseen Circumstance within

the existing commitments of the District under the District HCP.

7.3.2 Response to Determination of Unforeseen Circumstances

In accordance with the Service’s statutory authorities and obligations, which are controlling (50

CFR 17.22(b)(1)(iii)), after the conclusion of the process outlined above, the Service would

determine that an Unforeseen Circumstance has occurred, and that additional conservation

measures are likely required to address the circumstance but are not contemplated or capable of

implementation by the District HCP. Then, provided that the District has fully complied with the

terms of the District HCP, any proposed additional conservation measures by the District would

be limited, to the maximum extent possible, to those within the terms of the District HCP and its

ITP.

Under the Service’s “No Surprises” rule, additional conservation measures may not require the

payment of additional compensation by the District or its permittees. If additional expenditures

are required, the Service or any other federal agency may take additional actions that might lead

to the conservation or enhancement of a species that is being adversely affected by an

Unforeseen Circumstance. The costs of these additional actions are not intended to be borne by

the District and therefore are not included in this HCP’s funding commitment. However, prior to

undertaking or attempting to impose any actions or conservation measures, the Service may

consider all practicable alternatives to the proposed conservation measures, and adopt only such

actions or conservation measures that would have the least effect upon the economy and lifestyle

of the District and permittees, while at the same time addressing the Unforeseen Circumstance

and the survival and recovery of the affected species and its habitat. The purpose of this

provision is to recognize that Congress intended, even in the event of unforeseen, extraordinary,

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or Changed Circumstances, that additional mitigation requirements not be imposed upon a

Section 10 permittee who has fully implemented the requirements undertaken by it pursuant to

an approved HCP.

7.4 Clarifications, Administrative Changes, and All Other

Changes

Circumstances may arise that necessitate changes to the HCP and/or ITP. Over the course of the

ITP term, such circumstances are in fact expected. Changes will be one of two types: (a) simple

clarifications and/or administrative changes to the HCP and ITP, and (b) all other changes, which

constitute amendments. Amendments may include those actions or decisions that would affect

the scope of mitigation or method of implementation of the District HCP or ITP and would

require consent of the Service. Generic examples of amendments include but are not limited to

the following (although none are currently planned or imminently envisioned):

• Addition of parties to the ITP;

• Changes in the ITP geographic boundaries, with possible material effect on Barton Springs

flows during Extreme Drought;

• Additions to or deletions from the species protected under the HCP;

• Changes in state or local legislation that materially diminish the authority of parties to the

ITP to carry out the terms and conditions of the ITP;

• Changes in the conservation, monitoring, compliance, or enforcement programs likely to

affect the level of incidental take of species; and

• Renewal of the ITP beyond the initial term.

In considering a prospective change to the existing ITP, the District will provide the Service with

its analysis of whether the prospective take of the Covered Species would increase, decrease, or

stay the same with the amendment, and the basis for that assessment. The District will then seek

to consult with the Service as to its concurrence with the findings of that analysis. Any change

that increases take is to be considered an “amendment” under the Service’s statute, requiring

execution of the procedures described in subsection 7.4.2. Further, renewal of the ITP beyond its

then-current term or the issuance of a new ITP for the Covered Species will trigger a review

under National Environmental Policy Act (NEPA), and by rule is considered an amendment.

7.4.1 Clarifications and Administrative Changes

From time to time, it may be necessary for the Service and the District, as Administrator of the

District HCP, to clarify provisions of the District HCP or the ITP to deal with issues that arise

with respect to the administration of the process. Or the District may find it necessary to be

more specific regarding the precise meaning and intent of the language contained within the HCP

or ITP documents. Clarifications do not change the provisions of any of the documents in any

way but merely clarify and make more precise the provisions as they exist.

The District HCP may, under certain circumstances and at the discretion of the Service, be

amended without amending its associated ITP, provided such amendments are minor or technical

and that the effect on the species involved and the levels of take resulting from the amendment

are not increased from those analyzed when the ITP was issued.

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In addition, from time to time it may be necessary to make minor Administrative Changes to the

documents that do not make substantive changes to any of the provisions but that may be

necessary or convenient over time to represent the overall intent of the District and the Service.

Clarifications and Administrative Changes to the documents may be approved by the Service;

after review by the District’s General Manager or the President of the Board of Directors of the

District, such minor changes generally would be formalized by letter agreement or by substituted

Plan Documents modified to contain only the Clarification or Administrative Change.

7.4.2 All Other Changes

Other than Clarifications and Administrative Changes as described in the subsection above, and

subject to the Service’s concurrence with the District’s assessment that changes in take or

mitigation for an existing ITP occur, all other prospective changes are considered to be

amendments and will follow the procedures summarized in this subsection. The District HCP,

ITP, or any (future) Implementation Agreement with other parties may not be amended or

modified in any way without the written approval of the District (as Administrator of the District

HCP), all signatories (currently, only the District), and the Service. All proposed material

changes or amendments shall be reviewed by the District. Material changes shall be processed

as an amendment to the permit in accordance with the provisions of the Act and regulations in 50

CFR Parts 13 and 17, and shall be subject to appropriate environmental review under NEPA

provisions.

Amendments of the District HCP and ITP permit would be required for any change in the

following: (a) the listing under the Act of a new species not currently addressed in the HCP that

may be taken by project actions; (b) the modification of any project action or mitigation

component under the HCP, including funding, that may significantly affect authorized take

levels, effects of the project, or the nature or scope of the mitigation program with the exception

of those plan modifications specifically addressed in the original District HCP and ITP

application; and (c) any other modification of the project likely to result in significant adverse

effects to the Covered Species not addressed in the original District HCP and ITP application.

Any such changes constitute a requirement for an amendment to the HCP and ITP.

Amendment of a Section 10(a) permit must be treated in the same manner as an original ITP

application. ITP applications typically require a revised HCP, a permit application form, may

include an Implementing Agreement if another Plan Applicant is added, a NEPA document, and

a 30-day public comment period. However, the specific documentation needed in support of a

permit amendment may vary depending on the nature of the amendment.

Proposed amendments to the District HCP or ITP can be initiated by the District or Service, or

by other participating entities executing an Implementing Agreement, if they are approved for

addition after the initial ITP and HCP are authorized. A proposed amendment would be

submitted as a formal proposal to the District and Service for possible action. The proposal must

state the reason the amendment is being requested, description of the proposed change, and an

analysis of the potential effects of the proposed revision on the Covered Species and the terms

and conditions of the ITP. Additional information may be requested. The approval process is as

follows:

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• Action on a proposed amendment under the District’s jurisdiction must first be taken by the

District. In a timely manner, the District Board must approve or deny the request,

• The plan amendment would be referred to other potentially affected Section 10(a)(1)(B)

permit holders (here, the COA) for review and comment, and

• A plan amendment approved by the District Board (and any other parties to a future

Implementation Agreement, if any) would then be forwarded to the Service for action

consistent with its rules, regulations, and policy.

As specified by Service regulations, the same procedure would be followed when plan

amendments are initiated by the Service, such as listing of a new species that could result in a

change to the District HCP terms and conditions.

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8.0 District HCP Funding Assurances

Essentially all of the HCP measures to be put into practice by the District (including the

prospective avoidance, minimization, mitigation, and monitoring measures and their

administration) are now specified in and authorized by the District’s revised, approved

Management Plan (MP) (BSEACD, 2013). Most of the direct measures called for in the HCP,

including the District’s well permitting and drought management programs, are already part of

the MP and annual budget. As such, the funding for these measures over the 20-year term of the

District HCP constitutes a significant share of the District’s annual operating budget that is

already being expended in these efforts. The District’s budgeted revenue is based on water-use

fees from permittees and other related fees that are authorized statutorily and collected from the

District’s groundwater production permittees; and also from a statutorily mandated, substantial

supplemental fee paid by the COA, the amount of which is linked by formula to the water-use

fees paid by the permittees. These revenues will be augmented from time to time by

enforcement penalties and by other external funds for special initiatives, such as grants, neither

of which are under District control and therefore are not considered a part of the sustainable

operational funding of the District. Accordingly, because the continuing-operations budget of

the District is by law established to serve the District’s statutory purpose through implementation

of the District’s MP (and nothing else), a major share of the normal District operating budget

provided by continuing water-use fees paid to the District by its permittees in the ITP Area and

supplemented by the COA will in effect be committed to implementing the HCP incorporated

within the MP.

Because the HCP conservation measures are integrated with the Covered Activities, in that both

are groundwater-use management, it is not possible to differentiate funds for groundwater

management between Covered Activities and conservation measures. Similarly, there is no

separate or additional funding represented by the conservation measures in the HCP and the pre-

HCP periods; the difference is not how much is being spent but how those funds are being used.

Simply put, the District’s regulatory program for the Aquifer has evolved over the past decade

such that the District funds now support a much more effective groundwater management

program than the program that existed before the HCP, for essentially the same amount of

dollars.

The District HCP conservation measures, including the associated overhead activities, will

require variable expenses year to year, but always substantially more than one-half the total

funding of the District’s MP derived from use of the Aquifer in the ITP Area. Some flexibility in

annual funding of the HCP is needed by the District to ensure its continuing operations, which

also will contribute to the variability in expenditures among the years of the ITP term. The

actual level of effort and that portion associated with the HCP are expressed by the composition

of each annual budget, which is already being used by the District to defray the costs of the

personnel, programs, and special projects required to implement and manage most of the

conservation measures in the proposed HCP, as they are integrated with the Covered Activities.

The component parts of these budgets related to the HCP may also vary from year to year in the

types of expense involved. Because of these factors, the District considers it more appropriate to

commit to some minimum level of annual funding associated with the HCP conservation

measures, rather than an average level or the specification of an exact amount each year of the

ITP.

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The District is committed to fully implementing the proposed HCP and meeting ITP

requirements. Therefore, the District stipulates funding of the District HCP via its MP elements

during the term of the ITP will be no less than 60% of each year’s annual budget that is derived

from its statutorily authorized annual operating revenues related to Aquifer use in the ITP Area

(that is, not including use of financial reserves). For example, in fiscal year 2014, the District’s

Board-approved annual budget was approximately $1,717,000, of which $198,000 is from

reserves, so the nominal HCP Funding Commitment would be at least $911,000 for that year. In

most years during the term of the ITP, the actual dollar value of expenditures for the HCP will be

substantially greater than this minimum amount, as the execution of the HCP-related MP

provisions would routinely require and be associated with more than 60% of the total expenses

of the District. The funding by the District includes both in-kind labor provided by District staff

and directors, and cash contributions and expenditures for other goods and services, all in

support of the HCP conservation measures. The District’s annual financial audit report will be

used to document actual operational expenditures as being equal to or greater than the annual

percentage-based commitment to funding groundwater management and conservation under the

HCP.

Barring significant changes in the statutory authorities and/or legal landscape, which would

likely require a major amendment to the ITP and the HCP, the District anticipates being able to

continue annual funding from these sources in that same or greater amount because the revenue

is statutorily authorized. State law requires the District’s expenditures to be approximately

equivalent to its revenues (which may include use of financial reserves) each year. However,

also by State law the District cannot commit funds in advance to any purpose except those

budgeted each fiscal year, and it is allowed to budget for only one year at a time. These

restrictions notwithstanding, it is the District’s intent, as demonstrated by its Board’s agreement

to the ITP terms, to continue to fund all the activities that support the District HCP measures in

the committed amount, as a minimum, throughout the term of the ITP and HCP. The District

will report the actual funding provided for implementing the HCP each year in its annual report

to the Service.

The District will implement the HCP program in the form of District labor, program

expenditures, and/or cash each year for the aggregated HCP program in that year, which will

include the direct minimization measures and also various indirect measures that comprise

individual, time-phased projects active in that year, as authorized by the Board in annual

budgeting. For example, in the third year following ITP issuance, some of the HCP funding

might be earmarked to fund two project-oriented initiatives that could be active in the third

year—say, one research project and one mitigation measure, in addition to funding the ongoing

Direct HCP Measures. The specific time-phased funding commitments for the individual

Mitigation Measures are identified in their programmatic descriptions in Section 6.2.2.2,

Mitigation Measures.

Specific conservation-, research-, and mitigation-project measures will be identified and funded

in the out years, as other collaborating parties are identified and become involved, as required

funds from other parties are committed, and/or as participation agreements are negotiated. The

descriptions of the proposed individual mitigation measures and research projects, in Section

6.2.2.2, Mitigation Measures, and Section 6.4.1, Research Supporting the AMP, respectively,

provide a projection of the anticipated level of effort and the dollar commitments intended by the

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District for each such project area. These expenses are included in the annual funding

commitment described above. However, the actual years and the committed amounts (of in-kind

and/or cash contributions) under which any specific project measure is undertaken are uncertain

because the ability and efficacy to conduct those project-oriented measures and the timing of

them are not solely controllable by the District. The District will identify in its HCP annual

report those specific conservation, research, and mitigation projects that have been and/or will be

initiated and the project-specific District in-kind services and funding (and funding from other

sources, if applicable) that are planned for the then-upcoming year(s), once such clarity is

available during the course of the ITP term. Similarly, if, say, because of exigencies beyond the

District’s control some planned project was unable to be started when planned and/or was not

able to be funded at the planned level in one or more years, the District would explain the source

of the deviation from plan and any adverse effect on the HCP in its annual report to the Service.

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9.0 Alternatives to Taking

The Endangered Species Act (Act) requires that each HCP address “the alternative actions to [the

proposed incidental] taking the applicant considered and the reasons why such alternatives are

not being utilized.”

The Covered Activities in this HCP relate exclusively to groundwater withdrawals by third-party

well owners in the ITP Area and the District’s own regulatory program concerning such

withdrawals, which are superimposed on the natural variability of the Aquifer. The natural

variation in Aquifer storage and springflow together produce a condition in which any amount of

groundwater withdrawal during severe drought will constitute take. There is no alternative

action that allows use of the Aquifer as a water supply without producing take of the Covered

Species for substantial periods of time. Accordingly, any alternative that could completely avoid

take of the Covered Species would require imposition of a regulatory program by the District

that allows no use of the Aquifer as a water supply during drought.

9.1 Analysis of Potential Alternatives to Avoid Take

Two basic options were considered by the District in assessing the efficacy of an alternative

approach that could eliminate the use of the Aquifer as a water supply and thereby avoid, not just

minimize, take: reduction in demand for Aquifer water, and water-supply enhancement and

substitution. Under certain conditions, each of these, either individually or in combination, could

constitute an alternative to taking; they are evaluated in the following subsections.

9.1.1 Demand Reduction Alternative

The District’s authority allows it to mandate reductions in demand for Aquifer water, but only in

a limited sense. The District’s permitting program provides the means by which withdrawals

from the Aquifer by large-capacity wells and other wells of certain types can be controlled, both

in absolute-use terms and especially in response to drought conditions. These regulatory

curtailments, backed with effective enforcement to ensure compliance, provide a non-structural,

assured means for preserving the water levels in the Aquifer, which benefit well owners/users in

the western part of the District where saturated thickness of the Aquifer is relatively small; and

also, of critical importance to the HCP, such curtailments will benefit the flow and the DO

concentration of water issuing from Barton Springs, which is the habitat of the Covered Species.

However, the District’s authority does not extend to ordering complete cessation of withdrawals

from all wells in the Aquifer, even during Extreme Drought. Under State law and recent court

interpretations, landowners have a vested property right to withdraw groundwater under their

land as a real property interest. Further, the District’s regulatory program is supported by

permitting that is based on actual, reasonable and non-speculative demand such that there is very

little permitted pumping that is not committed to being fully used for beneficial purposes,

especially after factoring in severe drought curtailments. So the Demand Reduction Alternative

per se legally and practically must allow some amount of existing and future freshwater Edwards

Aquifer groundwater withdrawals from wells in the ITP Area to continue. The Aquifer has been

designated as a “sole-source water-supply” for many residents in the ITP Area, which imposes

certain protections and considerations applicable to other federal programs, including those of

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the Service. District regulation-mandated curtailments during drought that minimize but do not

prevent withdrawals and that are authorized under an ITP would be consistent with applicable

state and federal statutes. Such an alternative mitigates but does not avoid take (EPA, 1988).

9.1.2 Supply Enhancement and Substitution Alternative

During drought, if the District could mandate that all Aquifer users stop pumping their wells

during drought in favor of switching completely to another, standby supply, then the wells in the

Aquifer would not be decreasing springflow and increasing the amount and frequency of take.

The enhanced availability of alternative water supplies would facilitate and allow substitution for

Aquifer water. But as explained below, this Supply Enhancement and Substitution Alternative

per se is not statutorily, economically, or even physically feasible in aggregate for all

groundwater users in the ITP Area. The District is not legally authorized to make such demands

on its permittees, or even to require its permittees to develop and use alternative water supplies.

Some well-resourced permittees have voluntarily broadened their water-supply options to

include alternative sources of water, and some of them voluntarily curtail their withdrawals from

the Aquifer during drought, and use substitute supplies. But there are simply not enough firm-

yield alternative water supplies available now to all groundwater users in the ITP Area, either at

any price or at something less than prohibitive cost for their situations. In any event, the District

cannot legally mandate such substitutions per se for existing, authorized supplies of Aquifer

groundwater. The District can only encourage and incentivize acquiring such replacement water

by its scientific investigations and regulatory programs. With one minor exception, the District

does not own any alternative water rights, and its financial resources do not allow it to acquire

others, at least on the scale that would meaningfully affect springflow.

The District is actively working with its stakeholders, especially its permittees that are water-

supply providers, and with others to foster development of alternative supplies of water. The

District’s regulatory programs can be a driver in that. The proposed alternative can work for

some permittees in concert with the Demand Reduction Alternative described in the previous

subsection to provide a means for greater curtailments while meeting water demands, or a greater

likelihood of being able to meet the regulatory required curtailments. As new water supplies

become available, for example through desalination of brackish groundwater, aquifer storage and

recovery, and water reclamation, there will be increased opportunities to substitute those supplies

for Aquifer water. But the time frame for new supplies is not immediate, they are not likely to

be available over a wide geographic area, and they will be much more expensive than greatly

undervalued and underpriced freshwater Edwards Aquifer water in the ITP Area. Even if new

supplies were technologically possible, the District does not own or control those alternative

water resources, and if it did, the cost of alternative supplies that could provide complete

replacement of Edwards Aquifer water is orders of magnitude greater than the District’s existing

and likely future financial resources. So for those reasons, while the Supply Enhancement and

Substitution Alternative might support an option that is mostly based on demand reduction in

something of a hybrid way on a case-by-case basis, it is not per se an alternative that could be

used as the primary, preferred option in the HCP and avoid take.

The District has for years also worked to enhance the amount of recharge that can enter the

Aquifer through its natural openings in streambeds to maximize the amount of water available

from natural rainfall and runoff. One of the indirect project measures in the HCP commits to

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continue to preserve if not increase the recharge capacity of a major recharge location and

prevent the discrete recharge features from getting clogged with sediment-laden runoff.

However, few of those features are available to the District for such operations, too few to make

a real difference as additional supply. And the same dearth of alternative water supplies

described above prevents introduction of such alternative water into the recharge features during

severe drought conditions, which is when the additional supply is most needed.

Although structural projects and alternative water-supply projects such as those described above

can be important in management of the Aquifer, such activities are typically not under District

control or always available to the District. Provision of the entire volume of currently permitted

withdrawals from the Aquifer (nearly 2.9 billion gallons, or 11 billion liters, annually) with

alternative water supplies from non-Aquifer sources to even the current (2014) Aquifer users in

the ITP Area would be prohibitively expensive (into the hundreds of millions of dollars); and no

mechanism is available to the District to recover most such costs. Thus, to a substantial extent,

the District cannot afford the level of infrastructure development that would replace all of the

current water supplies of the Aquifer and allow large-scale substitution of water supplies.

Without such complete substitution with alternative water, take of the Covered Species would

continue during drought periods. Moreover, the District has no legal authority to force an

existing groundwater user to stop using that groundwater supply in favor of another. Further, the

District cannot legally, unilaterally reduce the property interest in groundwater from the Aquifer

even if a substitute supply is provided.

9.2 Basis of Proposed Groundwater Management Program

The District has concluded that the primary option that produces the needed balance between

legal groundwater withdrawal/use and conservation of the Covered Species is the non-structural

regulatory program that constitutes the Covered Activity; that is, the Enhanced Best Attainable

Alternative described in Section 6, Conservation Measures. The basis for this determination and

selection is discussed in this section.

The District is a political subdivision of the State of Texas, a groundwater conservation district

(GCD) charged by the State legislature to preserve, conserve, protect, and prevent waste of the

groundwater resources within its jurisdictional area, and to allow use of the groundwater

resources to the maximum extent feasible by well owners in that area. More importantly, the

District is the only governmental entity that is able to serve that mission, as the groundwater is

owned by the surface landowner, rather than the State or the public, and the landowners have a

legal right to withdraw water from the Aquifer for the beneficial uses of their choosing. Without

the District’s programs, groundwater withdrawals in the ITP Area would be unregulated and

discharge from Barton Springs would not be managed, raising the specter of zero springflow for

periods of many months during Extreme Drought. And without the District’s regulatory

restrictions, there would be no control on the impacts of springflow-induced stress on the

Covered Species.

Further, the District as a GCD has a legal requirement to manage the groundwater and protect

other related natural resources, including the Covered Species at Barton Springs. An ITP’s

required HCP offers a vehicle that can provide longer-term, more systematic assurance of such

protection than would otherwise be available to the District without the permit. It also provides a

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legal shield for not only the District but its permittees against claims that could otherwise be

asserted against them, as they exercise their legal right to use their “fair share” of groundwater

under the Act, which obligates real property owners to protect endangered species.

Within this selected approach are options related to balancing risks to continued District

operations and rewards in terms of aquifer and habitat protection, which the District developed

over time for this HCP as described in Section 4.1.2, Historical Perspective of Covered

Activities. The District Board considered several of the intermediate steps as potential options

for the HCP program, each having differing levels of curtailment and resulting springflow but

also with differing implementation challenges and probabilities of success. But ultimately the

Board determined that the District had an obligation to provide the maximum protection to the

endangered species that it legally and financially could, so the only acceptable optional level of

demand reduction in the final analysis is the Enhanced Best Attainable Alternative aided by

alternative-supply enhancement and substitution where feasible. This alternative comprises the

minimization, mitigation, and adaptive management measures described in Section 6,

Conservation Program. There is a practical limit on how much regulatory curtailment of water

use by any one permittee is feasible, and also a legal and financial limit on how much

curtailment is “reasonable” and “fair,” before a regulatory taking ensues that arguably represents

compensable loss to the groundwater owner/user. The Board considers the current expression of

this option at that limit, which constitutes conservation measures equivalent “to the greatest

extent practicable.”

The Enhanced Best Attainable Alternative, based on a hybrid of regulatory-based demand

reduction and alternative supply development, is considered the preferred and proposed option

for groundwater management in the ITP Area that affects the Covered Species, both now and

over the term of the ITP. At its maximum curtailment expression, this alternative, which

constitutes the Covered Activities, essentially results in water levels and springflows that would

meet the Desired Future Condition of the Aquifer, which is specifically implemented to

minimize take during a recurrence of the drought of record (DOR) to the maximum extent

feasible.

In summary, the Covered Activities of this HCP provide the primary vehicle to minimize the

risks of both incidental take of the Covered Species and compensable regulatory take of real

property. The District’s regulatory program is the only statutorily authorized option that the

District can use to balance both, and therefore it is considered the principal option for Aquifer

groundwater management in the HCP.

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10.0 Other Information That Secretary May Require

This section of the Habitat Conservation Plan provides assurance that no other information

besides that contained elsewhere in this document is required to be presented for compliance

with Section 10(a)(2)(A)(iv) of the Endangered Species Act. The Secretary of the Interior and

the Director of the U.S. Fish & Wildlife Service have not identified other specific informational

or other requirements of the District for this HCP at this time (2017).

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11.0 References Cited

Abell, R. A., D. M. Olson, E. Dinerstein, P. T. Hurley, J. T. Diggs, W. Eichbaum,

S. Walters, W. Wettengel, T. Allnutt, C. J. Loucks, and P. Hedao, 1999,

Freshwater Ecoregions of North America: A Conservation Assessment, Island Press,

Washington, D. C., U.S.A.

Alcamo, J., M. Florke, and M. Marker, 2007, Future long-term changes in global water resources

driven by socio-economic and climatic change: Hydrological Sciences Journal, 52: 2, p.

247–275 (April 2007).

http://dx.doi.org/10.1623/hysj.52.2.247

Arnold, S. J., 1977, The evolution of courtship behavior in New World salamanders with some

comments on Old World salamandrids. p. 141–183, In: The Reproductive Biology of

Amphibians, D. H. Tayler, and S. I. Guttman, eds., Plenum Press, New York, New York,

U.S.A.

Backlund, P., A. Janetos, and D. Schimel, 2008, The effects of climate change on agriculture,

land resources, water resources, and biodiversity in the United States: Synthesis and

Assessment Product 4.3 Report by the U.S. Climate Change Science Program and the

Subcommittee on Global Change Research, Washington, D.C., U.S.A.

Banda, N., J. Beery, and K. Holland, 2010, Estimation of exempt well use in the Barton

Springs/Edwards Aquifer Conservation District: unpublished BSEACD report, August

2010, 7 p.

Barton Springs/Edwards Aquifer Conservation District, 2003, Summary of groundwater dye

tracing studies (1996-2003), Barton Springs segment of the Edwards Aquifer: Un-

numbered, unpublished District report, April 2003, 6 p.

2016, Rules and Bylaws, as adopted on April 28, 2016.

http://bseacd.org/uploads/081816FINAL-BSEACD-Rule_MASTER.pdf, last accessed

January 18, 2017

2013, District Management Plan, TWDB-Approved on January 7, 2013.

http://www.bseacd.org/uploads/Financials/MP_FINAL_TWDB-

approved_1_7_2013_Body.pdf and

http://www.bseacd.org/uploads/Financials/MP_FINAL_TWDB-

approved_1_7_2013_Appendices.pdf

2014, An Excel-based spreadsheet model for estimating adverse effects on the

salamander populations at Barton Springs under various groundwater management

scenarios, July 2014. [to be completed]

2017, District Management Plan, TWDB-Approved on November 21, 2017.

http://bseacd.org/uploads/MGMTPLAN.TWDBApproved112117_reduced.pdf

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Brooks, B. W., J. T. Scott, M. G. Forbes, T. W. Valenti, J. K. Stanley, R. D. Doyle, K. E.

Dean, J. Patek, R. M. Palachek, R. D. Taylor, 2008, Reservoir zonation and water

quality: Science, management, and regulations. LakeLine 28(4): 39–43.

Brown, B.C., 1950, Texas Natural History Museum Collection, specimens 6317–6321.

Casteel, R., M. Musgrove, B. Hunt, and B. Smith, 2013, Evaluation of a hydrologic connection

between the Blanco River and Barton Springs in central Texas using discharge and

geochemical data: Geological Society of America, South-Central Section Annual

Meeting, San Antonio, Texas, April 4–5.

Chamberlain, D. A. and L. O’Donnell, 2002, City of Austin’s captive breeding program, Barton

Springs and Austin blind salamanders annual permit (PRT-839031) report: January 1–

December 31, 2001, City of Austin, Watershed Protection Department.

2003, Annual Report (January 1–December 31, 2002): City of Austin’s captive breeding

program for the Barton Springs and Austin blind salamanders, City of Austin, Watershed

Protection Department.

Chen, C., D. Gillig, and B. A. McCarl, 2001, Effects of climate change on a water dependent

regional economy: A study of the Edwards Aquifer, Climate Change 49: 397–409,

Kluwer Academic Publishers.

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